I switch between Python and Julia frequently with Julia being my main language now (formerly Python). It's not as big a problem as people seem to think. If this is your biggest difficulty you're not doing difficult stuff.
Same. I haven't made a mistake on this issue for a long time despite switching languages with conventions frequently.
The only thing I will say is terrible is I believe julia had something you could do to make it a 0 indexed language just for you? That seemed like a terrible idea, haha. I have never seen anyone use it thankfully
You can't make the language 0 based, that would indeed be a terrible idea. Instead, you can make array types which have whatever indexing behaviour you like.
I think it's less about difficulty, and more about causing bugs when you're having to switch back and forth between indexing styles. It's just a footgun; it's not difficult to not pull the trigger, but if you do it often enough, statistics start to kick in.