Very simple, decide who you want your audience to be. Sometimes reaching out to other people who might struggle with English is a worthwhile effort (e.g. when hiring locally). Sometimes, you just want to reach as many people as possible regardless of where they are. In that case, English is the way to go.

But put bluntly, there are very few senior developers out there who are unable to read what is going on in mainstream English fora, books, etc. You have to be able to take that information in if you want to be able to operate in a professional way. Most of that information is English only. And of course part of being a senior dev is being able to contribute in a meaningful way there as well. It's not a read only thing.

I understand a lot of people have reservations about expressing themselves in a language that is not their own. Things like grammar are tough and mostly people are very tolerant but not always.

Btw. you might want to check your title for grammar ;-), just saying.