I’m not sure what the FLAIR piece means, but foci in the subcritical white matter typically means brain lesions. They are know to cause headaches/migraines, so it’s possible they could be related to your seizures. Small lesions aren’t as concerning as larger ones but you’ll want to keep monitoring them to see if they grow or if you have any more appear. I have an annual brain MRI to check mine.
FLAIR refers to "Fluid-attenuated inversion recovery ", a type of MRI image.
Many, if not most, people develop foci of hyperintensity in the white matter of the brain. This comes with aging, as a few of your cells lose their oxygen supply.
These are likely unrelated to your seizures, your cognitive abilities, or anything else that matters.
They mean you're older than you used to be and there are spots on your MRI to show it