I think the interaction/communication problem exists as you have realized, but you are focusing on the wrong point. It's not about what terms we use to address our parents' peers. It's about the behavior that our (Nepali) culture dictates. If you speak up to older people, you are rude. If you nod agreement to whatever they are saying, you have good manners. In Nepal, I called my friends' parents uncles/aunts and stayed quiet around them and I was always praised for having good manners :) Now, in the US, I call my friends' parents by their first names. But I still find it uncomfortable engaging in conversations with them and if they ask me something, I end up giving the shortest answer possible. So, I don't think it has anything to do with what you call them. It's the culture that we grow up in.