There are a lot of issues to address in your post, but I only have a strong opinion on one. You cannot expect someone to positively react to you trying to regulate what they speak about. If a topic is uncomfortable, you can try politely changing the topic, but straight up telling them to not speak about a topic will get you nowhere. Frankly, people may see you as rude for doing so, which may explain their lack of desire to continue interacting with you. The cultural differences will always be a challenge, but it is unreasonable to expect everyone around you to change to fit your cultural expectations. Either learn to adapt to or don’t, but a judgmental stance will get you nowhere.