There are currently 58 search results for "Columbia" on space.se (although a few are unrelated to the orbiter), and a large amount of them refer to the Columbia disaster, on mission STS-107.
There are also a few questions centered on the Columbia orbiter only, and not the disaster or the rest of the Space Shuttle program.
Now, there is a columbia tag. It is assigned to two questions.
There is also sts-107 as a tag, with only one question (that also has columbia)
Is a mass retagging needed for Columbia? Or should columbia and sts-107 be removed instead, because space-shuttle optionally coupled with failure is enough?
I personally believe having both columbia and sts-107 is redundant and just columbia suffices, as any question on STS-107 would probably have columbia too.