I'm pretty sure this is because very few users actually use any of the search qualifiers (eg all they ever do is type in the words they want). And they certain

I'm pretty sure this is because very few users actually use any of the search qualifiers (eg all they ever do is type in the words they want). And they certainly have the data to verify this. I bet someone decided to the L10N (it was not there at launch) for the label display name (as you observe), and certainly knew they were not addressing the search bar (that would be a much harder change), but figured it's ok since so few people use it. It sort of makes sense to do the relatively small amount of work needed for the daily use of 99% of your users rather then get stuck on the really hard part for the last 1%.