Comment by andy_ppp

Because if you want your project to be well used and contributed to you’re probably writing it in English. I don’t see too many French or Arabic or Chinese or British English open source projects that have taken off, but I’m happy to be proven wrong…

Even large open source projects built in China like Ant Design have documentation and interfaces in American English because even if you don’t like it it’s the correct decision to not needlessly buck against patterns laid down in the programming environment you’re working in.