not a twin but man I've seen some really weird shit about that theory lmao, there was a murder case about two twins that were split up and they did have some weird connection growing up, like they were missing something until they met
Parents said they would act weird whenever one of them was also acting weird, it's so complex and when you think about it just the existence of twins is so "surreal"
You don't sound ignorant. There is no exact science to it, however, there is a special connection between twins. I've had some times when I'm hours away and feeling bad then I'll get a call from my twin checking on me. The "twin telepathy" thing in my opinion is just us knowing eachother so well that we already know what emotions the other is feeling or behavior habits that may come into play
As a twin myself, I despised dressing alike when we were children. You really can't get a sense of self identification when you're constantly looking at a "mirror image". When no one can tell you apart it makes it soo much worse when you want to break free. Early socialization should also have been done then maybe just maybe Yuha wouldn't feel then need to be glued to Yui. This is just my POV as a twin.