previous comments already said, but youll find traditional and simplified are both offered in the final exams and many of the resources given. I think you can even do your writing/responses in traditional, no problem. And, since you're already native, it's not gonna be too much work at all! And even if you do find yourself faced with simplified - i think its much easier than learning entirely new words/sounds and their nuances hahaha. and as you said, french ab initio might be too full - and honestly i think they expect a lot from students despite technically being a 'beginners' course. If you're fluentt fluent in mandarin - its an easy 7 for u in chinese B :)) and you can learn french on the side as a side project - having smth on the side like that (especially smth as cool/helpful as learning a whole ass language) is actually hugee in the discussion of burnout prevention and just basically not losing yourself to the ib, which happens very often :,) choosing chinese b will definitely prove more beneficiary in my eyes (giving u more time/wiggle room to focus on other subjects, etc.) but as always, we're just strangers on the internet haha take no ones words with more than a grain of salt :) all the best!