A recently added tag was created with the UK English spelling flavour. Many US English speakers may have trouble finding or be hesitant to use this tag. Is it possible to create a tag that refers to this one with the alternate spelling?
How do I propose or vote on tag synonyms? Users with this privilege and a total answer score (total upvotes minus total downvotes) of 5 or more on the tag, can suggest tag synonyms. Users with a total answer score of 5 or more on the tag, can vote for tag synonyms.
They're a thing and they can be created by higher-rep users, and they do what you want. Now that you pointed out the tag and its synonym, this can be done by somebody with the appropriate score in the tag.