Hi, Erloto.
There is nothing saying that you can't write your story in your native language. There are plenty of polylingual people here and many English-speakers who aren't above running an entire story through Google translate. So, your story will be read, no matter what language it is written in.
About the tags, I'm not even completely sure why we have tags. They aren't used to organize or make it easier to search for stories, so they're really rather pointless. Just state in the story's summary what language you wrote the story in.