Why do you have to address people? I've gone years without knowing someone's name, I'm really bad at names. And then you get to the weird social situations

I was close enough with my friends family in high school that I used to hang out with them years even after he moved away, at least a few times a month for almost a decade.

I have no idea how to address them. Do I say Mr/Mrs X? Do I call them by their first name? Do I call them Aunt and Uncle in another language like what is normal in their culture?

I have no idea. So I just didn't. For years. Occasionally it's awkward, like at a party when it's loud, but not so loud you'd need to tap them... So I'd either wander around and repeat the approach, start talking to someone near them (sometimes even refer to them via relationship with the person I'm speaking to to get their attention), or pretend like I just remembered something so I could make a noise without it being psychotic.

I think I brought it up with my friend and his sister a couple years in, and they thought it was hilarious, but said any of those options would be fine... Which I did not find helpful.

But again, you'd be shocked how easy it is to avoid it. Compared to that, you can just say "excuse me" or "sorry to disturb you" or whatever... Humans are really, really good at noticing when someone is talking to them