Unless I'm completely mistaken about the concept of tag synonyms, I believe there is a bug in the validation logic on the tag synonyms page.
Failed to propose synonym:
Version specific synonyms can only be created by moderators
Should a tag really be presumed to be a version tag if it is preceded by a single numeral?
I can understand why the following would be presumed to be version-specific tags:
But those all use a numeric suffix, not prefix. If this behavior is as designed, then perhaps a moderator could add 9patch as a synonym for nine-patch?