In as much as the local board doesn't say "do not post in English language" any one is permitted to post with whichever they wishes on either your language or english is acceptable. I know in locals there are some people who aren't comfortable posting with their languages so they uses the one which they finds it interesting to post with, your main interest should be focused on whether the post is readable or not, meaningful and conveying the required information if not on topics then such post should be reported to the mod for immediate deletion.