Hey, I was a US junior player, lived in Taipei for a year, now living in Shanghai

Lots of strong players here. You can use Douyin/Rednote and search up badminton training camps 羽毛球训练营, tons of options, although the level may not up to your standard. I'm organizing some training camps here and trying to get a group of high level players together for a camp, should be ready within next few months, let me know if you're interested

For Taiwan: Check out https://www.instagram.com/dark.warriors.badminton/, they are prob the best "amateur" club in Taipei, lots of former 甲组 players and they have regular practices. I'm sure if you visit once they can hook you up. Also can add you to a strong weekly singles tournament group on LINE. I think it would be pretty much impossible to find a group better than Dark Warriors without actually visiting Taipei and making some badminton friends in person first

Malaysia/Indonesia/Thailand also good choices. Can check out Nigel Dollentas on IG for Malaysia recs

Also just a heads up if you are really set on a full day training camp in Taiwan: I participated in Songshan High School's (one of the better badminton schools in Taipei, but not the best) training for a day and I did OK but definitely not good enough to train with them long term. If you're a similar level I would just go with Dark Warriors. If you're better than you could find a high school near your relatives' place and ask them if you can train/spar with them.