I know it can come off as harsh and off-topic, but I say this when I see the signs because I wish someone had done the same for me. I spent the first 35 years of my life bouncing around from topic to topic, taking on far too much, achieving far too little, and generally turning my life into a hot mess. No one ever told me I could have ADHD, nor would I have known the signs to recognize it (since the reality of executive disfunction disorder is not the popular image of ADHD).

OP is asking if he should try learning 3 new languages over the next year. If he has the problems with focus that his post and submission history indicates, then he has a snowball's chance in hell of succeeding without medication. But properly medicated he probably could.

So OP: if you want to learn 3 new languages in 2021, consider seeking psychiatric help. Not a dig, just advice from a fellow ADHDer.