Ahh, sorry you have this worry for your niece. I would take evaluations further. I would have her evaluated by a developmental pediatrician or an occupational therapist. This could be speech related but speech also plays into other neurological issues. There are three parts of speech that all have to work. First, there is receptive, that she has to take in what is said to her and organize it so she can understand it, comprehend. The next part of speech is expressive speech. This is where she organizes her own thoughts in order to then have a response to express either through words or actions. And third is articulation which is actually saying the words. Motor skills of the mouth are involved but even more so, those connections in the brain through nerves. My son has sensory integration disorder which is when his nervous system doesn't communicate properly. Speech is often involved. He also had trouble chewing and avoided all things like meet or chewy items. He gagged when he ate those. Not knowing how to play with toys. Not responding to commands. And avoiding eye contact are all signs. There is also autism which is different than sensory integration disorder although sometimes they can overlap. We got help for my son early with an evaluation at age 3 by an occupational therapist. He did occupational therapy for 6 years. He really functions very well now. But that early intervention was key. So, I'm glad your niece is doing speech therapy but would also suggest further evaluation.
That she does hand you things when she needs help is great. That's a way of communicating and she is putting the pieces together to do that. It's a good sign.
No, do not discipline for things currently that may be due to the issue of understanding and communication. I made this mistake with my son of being a little hard on him when he was doing the best that he could. He's always suffered low self esteem and to this day, I hope that I did not contribute to that by my own lack of understanding early on of his struggles. There is a phrase the first OT we saw told us and it's my mantra with kids that have challenges. Accentuate the positive and minimize the negative. This means to celebrate each positive she does and in a big way. And to not focus just on her deficits. Compliment and enjoy her sweet smiles even if she doesn't want to make eye contact just yet. (and OT"s teach strategies for such things she can employ later like looking at forehead instead if eyes are too much.)
We're here to help so let me know what you think!