I learn I've become less of a grammar Nazi with may language learning. There are certain mistakes I don't think native speakers should be making, but I also realize as a Swahili speaker that my grammar in literary form is horrendous simply because I rarely write or read in it and mainly speak it.
I don't pause to think of grammar rules yet when I write, I have to sit there and stew about very simple things.
On that note, find myself "learning" Swahili all over again because I've never stopped to think why I use cha, la or ya. It just comes to me naturally.
I attend a French meet up monthly and there's a lady who's a native Spanish speaker and since I'm learning Spanish from the bottom, we were discussing the Spanish alphabet and she could barely recite it.
My English simply happens to overpower every language because it is not only one of the official languages of Kenya but it's been beaten into me through my love for reading.
On this topic though, it does annoy me when I see people not capitalize I.