Stream owners get to set the Submission Rules for their streams. The owner of Imgflip's featured streams and probably owners of a few other streams are currently using the English language only rule.
You can look for streams that allow languages other than English here:
imgflip.com/streams or create your own stream with your Submission Rules here:
imgflip.com/create-stream
Fun fact, everyday many thousands of people from all over the world make images on Imgflip, in virtually every language spoken on earth. Most of those people don't have Imgflip accounts and therefore can't submit their foreign language images to the Imgflip Community. They usually download and post their images somewhere else or share the image page link elsewhere. Occasionally a foreign language meme will get submitted to the fun stream and make it through to featured status, those are against the rules though.
Caption this Meme
