Shouldn't we have a tag for bluegrass? There are tags for Blues and Rock-n-Roll, rightly so. I asked in What's going on in Soldier's Joy? whether we should also have this tag.
Tags are generally created as needed, not because we could have questions with a particular tag. In the past we have typically waited until a few questions have been asked that may benefit from having a tag created for them.
Your Soldier's Joy question is off topic here anyway, so up until now we have no questions that require a bluegrass tag.