But that was an answer. It means not the engines, not the dish, not the saucer, not the shuttle bay. It may not be specific, but in the heat of battle, it's enough information for Kirk to know the ship's in trouble. The words "major" and "hull damage" being the keys.
Gatt is a computer who is interfaced with the ship's computer. He shouldn't be giving cryptic clues about where the damage is or isn't. I'd have serious problems with the software company if they gave me a program that can't answer a question directly!
He should have been able to say exactly
where the hull damage was: decks 12-15, port engineering, aft nacelle, etc...
Of course, maybe the Enterprise took such a hit the computer was damaged, and his response was a 23rd century version of:
"Where's the damage?"
Command not found.
In that case, it would have been a nice nod to TOS to have smoke come out of his ears.