I think I am basically 95% bilingual, my native language is not English, but it was thought in school from first grade (age 5 or 6) all the way to high school (17 years old), and then in post-highschool education, I also had 2 mandatory English courses. The thing is having learned so early is I was too young to realize when I could start entertaining a conversation in English without thinking because it was almost always like that for me.
I do think though that when you can think in your 2nd language without having to mentally translate in your head to your native language is when you’ve reached a level of fluency that is good enough to be called bilingual. I would probably say, if you can understand jokes and plays on words in your second language, that’s probably a good indicator that you are fluent
The last time I used arch it worked fine for 6 months then it needed to be scrapped because the network fully stopped working after an update. I’ve been on fedora ever since without a single issue. Arch is fine for personal devices where you can afford to spend half a day on troubleshooting a package that is too recent and straight up doesn’t work because there’s no real testing being done. I wouldn’t put it on a work device simply because it’s not a just works distro