OM... Was going to just leave to others, but since no one else seems to be willing to have the courtesy to reply....
My first thought is that we have too many tags as it is. Pretty soon the pages will be filled with tags making them near useless for the stated goal of filtering a large batch of covers.
My second thought is what counts as "award winning"? We would likely have to create a list of awards that are deemed prestigious enough to justify a tag (e.g. Grammy vs. Bubba's Songs of the Year). Similar to the Rock & Roll Hall of Fame vs. some local music hall of fame.
Also does an award for mixing, editing, etc. count?
Why just the song level? There are awards for albums and artists as well.
No expert, but my understanding is that the Grammy is international while the Brit and Juno are limited to a nationality (UK and Canada respectively). Should these restrictions affect tag-worthiness?
Taking all of that into account, I can only see allowing an "award winning" tag for a Grammy, Oscar, Tony, etc. won in one or more of an agreed upon group categories.