This is definitely a very good observation, but I still honestly think the country flags in the local boards doesnt mean much, it's probably just a way to identify with what part of the world makes up that community, it does not necessarily mean that every body in that community must come from the same country, what matters is that they all speak the same local language and understand themselves perfectly.
Take for example, we do have our own Nigerian local board with our flag, but some times, I do see comments from non Nigerians, and even I myself also do at times, post on other local boards that is not a Nigerian board, but is English or pidgin speaking, like for example, the Ghana 🇬🇭 local board.
So, for me, I've always seen the flags as a symbol of the language of the people that make up that community, and not the country itself, and what this means is that, any body from any part of the world that understands that language can participate in discussion on that board.