Another one I keep seeing is "should of" instead of "should have." Go figure.
I think if someone spends a long time studying English, it is possible to get really good at it. Especially in writing: while speaking may present its own challenges (e.g. pronunciation and accent, as well as inability to articulate thoughts in a conversation "on the fly"), writing allows one to think and lay out their thoughts coherently, and edit as necessary.
I have read some non-native English writers on Medium that write at least just as good as their native counterparts, if not better. And that does go for content too! Foreigners bring a unique perspective that Americans may not be aware of. English is also my second language, but I started learning it early in life, even before I went to elementary school. By now I feel practically bilingual.
By the way, I think your English is great. Just based off your writing, I would not be able to tell it's not your native language!