In terms of finding surgeons, at least in the US there are sometimes publications (newspapers or city magazines) that periodically do "best doctors" lists where the doctors are chosen by who other doctors would go to for treatment, presuming they are more able to find the best than the public would be. You could ask eye doctors like optometrists who don't do cataract surgery who they refer people to, or who they would go to. In my case when searching for a surgeon abroad I also looked for surgeons who had participated in clinical trials for new IOLs because it seemed likely a sign they would at least be competent since it seemed likely that those who ran the trials wouldn't wish the results tainted by bad surgical results (though I hadn't confirmed that speculation, it seemed it couldn't hurt to narrow down the field). I figured surgeons who were on faculty at medical schools, or were asked to be on industry panels or quoted as expected in trade publications might at least be respected for their medical judgement by some (which is separate from physical surgical skill of course, though hopefully medical professors are skilled enough to teach others).
If you are considering premium lenses, one concern is that you need to be comfortable with the very tiny risk that visual artifacts might lead you to wish to have a lens exchange, which is also a very safe surgery but does have very tiny risks just like cataract surgery does. The majority of people with premium IOLs are happy with their choice and would recommend them to others, but its necessary for someone
Lens powers aren't an exact calculation, they are estimated based on statistics of prior patients. They tend to be accurate for most people, but there is a higher risk the power may be off in a high myope like you. That means you also need to be prepared for a chance you'll need laser surgery afterwards to fine tune your refractive error if you wish to avoid wearing glasses/contacts.
The doctor noted that you'd like need surgery in the 2nd eye to balance vision due to being a high myope. In my case thats what I chose to do since I felt a sense of imbalance between the two eyes after the bandage came off my first and the other had a contact lens, even though my 2nd eye wasn't as myopic, it was only -6D or so. (though since I traveled for surgery I didn't give it time to see if I adapted quickly, I had to decide that day). However some people do seem to manage ok with a contact lens in the 2nd eye. It seems like your corrected vision is reduced in both eyes already so it seems likely you'd want to go for it anyway.
The decision about which lens to go with partly depends on which visual ranges are most important to you, e.g. how much really near vision is important to you since that is one difference between the trifocals vs. the Symfony. The trifocals give decent intermediate, but most studies put the Symfony ahead of all the trifocals (though I saw one statistical outlier recently where the FineVision trifocal was behind the Symfony at distance and at 1 meter, but oddly slightly ahead at 2 meters). Of course studies are just averages, some have great intermediate with a trifocal (but then they might have had even better with the Symfony). One study I saw a year or so ago of the premium lenses out at the time suggested from 46 centimeters outwards the Symfony had the best results. So the question is partly how much nearer than that you use how frequently, and whether that is worth a slight added risk of nighttime vision problems (or need to exchange the lens due to them), and a slight reduction in intermediate.
Unfortunately if your eye isn't fully healthy, its possible the results might be less than average, studies only report averages.
I debated up until the week of my surgery whether to go with a trifocal or the Symfony, but went with the Symfony in part since intermediate and distance were more important to me than very near. The graphs showing the level of near for the trifocals appear very tempting, but in reality that near is mostly past the "point of diminishing returns" for many people. I figured the odds were I'd get near enough with the Symfony, and though even more might be of use but not worth the reduction in intermediate&distance, risk of halos&glare, and risk of reduced vision in dim light (due to the light being split to different distances), etc.
I figured worst case readers for near occasionally would be less of a big deal, I could always use a magnifying app on my smartphone worst case for fine print. I wound up 20/25 at best near, at least 20/30 when measured at 40cm and since they didn't have a 20/25 line it might have been 20/25, since I read some off the 20/20 line). My results seem to match the studies, but my eyes are healthy aside from this, I have 20/15 at distance (at least, they didn't have a line below to test), so nothing is reducing their visual potential as it might in your case.
If you went for a trifocal, there are 3 major ones approved there, the AT Lisa Tri, the FineVision and more recently the Alcon Panoptix. At the time I had my surgery the Panoptix wasn't out yet and the FineVision and AT Lisa Tri seemed fairly comparable, some surgeons preferring one or the other, but perhaps the AT Lisa Tri having a slight edge, now though I think it might be the FineVision out of those two, with the new Panoptix perhaps leading those but not enough data to know for sure. They each have slightly different intermediate adds which correspond to different best intermediate focal points. Do you happen to know how far your eyes are from the computer screen? (it varies quite a bit, especially between those who use laptops vs. separate large computer monitors).
Surgeons seem more comfortable using the Symfony in cases where they wouldn't use a multifocal, but data on the issue is limited because surgeons are cautious about taking risks. Here is one article on:
http://www.healio.com/ophthalmology/education-lab/2016/12_december/the-importance-of-depth-of-focus-extending-range-of-vision-with-a-new-class-of-iols/symfony-iols-in-challenging-cases
"Symfony IOLs in challenging cases"
I don't know how much technical background you have, if you can manage to deal with technical jargon in industry publications. In case you (or others) can, or can get some use out of these skipping over parts you don't understand, one of the earliest articles comparing the Symfony to the AT Lisa Trifocal by a UK author is here:
http://ophthalmologytimes.modernmedicine.com/news/vision-all-distances?page=full
A more recent one led by the same author comparing the Symfony to the AT LIsa Tri and the Finevision trifocal is here (links on the page to PDF or html versions of paper):
http://www.scirp.org/Journal/PaperInformation.aspx?PaperID=69937
That is the one with an outlier data point with the FineVision ahead at 2 meters that I hadn't seen elsewhere.
The Symfony lens seems to be more tolerant to residual astigmatism than at least the multifocals this tested (though I've seen similar results):
http://www.scirp.org/Journal/PaperInformation.aspx?PaperID=73363
this just tested the Symfony to show its tolerance to refractive error:
http://www.scirp.org/Journal/PaperInformation.aspx?PaperID=73889
Start by reading this article carefully and twice:
http://www.medhelp.org/user_journals/show/1648102/Consider-ALL-the-Options-Before-Your-Cataract-Surgery-Working-Through-Whats-Best-For-You
You need to clearly understand the problems and risks you are taking because they are significant. Let me start by saying your had surgery and it went perfect and you had no problems and your eye saw 20/20 without glasses (with a toric monofocal IOL). Your would not be able to use your eyes together because of the huge difference in refractive errors (your LE is -9.25) so even with contact lens LE they would not work, glasses would not work, you would have to have cataract/IOL surgery RE to balance off or surface PRK refractive surgery if eye has NO cataract.
A retinal detachment (RD) is relatively rare in the general population about 1 in 10,000 to 20,000. After successful Catract/IOL surgery in this group the risk of RD is about 1 in 3000 to 5000. In high myopes like you the risk can be as high as 1-3% but once you have RD in one eye risk to other eye is as high as 10-20%. After cataract surgery the risk could be 10-25%. The RE may have had a "scleral buckle" and the retina is treated and re-inforced thus cataract IOL surgery on RE may not significantly increase risk post op. You would need to discuss that with the retina surgery or ophthalmologist who can look in your eye. If your RE has good visual potential and saw 20/20 (6/6 metric) after the RD surgery before the cataract IOL surgery you might be a candidate for a premium IOL like synfony. However if you did not recover full vision and your have macular damage then premium generally not considered a good choice.
The risk of RD does not decrease with age. It increases after cataract surgery which is generally done in mid-late 70's The only think I can think to support that is that RD usually occurs because of posterior vitreous detachment when gel in eye strips off retina. Once it's completely stripped off and not touching retina the risk diminishes. Because most people older than 75 have had PVDs if they do not have cataract surgery a case might be made that they are at less risk than when younger with no PVD. In anycase I don't think as a true generalization it works at all.