Regex For Stream Tags

Twitch announced the new custom tag system, and they mentioned in some documentation that tags need to be alphanumeric, no spaces, with support for some accent marks. I am designing an application for managing/automatically applying stream tags, and I want to validate these tags prior to trying to apply them to a stream. Unfortunately, when it comes to regex, allowing accent marks and tags in non-Latin languages (ex. Korean, Japanese) complicates things.

Is there a known/official regex for tags? I tried searching for one to no avail. If not, it would be a good idea for Twitch to release one in their developer docs.

Any help is appreciated, thank you!