FYI: the adjective старый|ая|ое (old) has the cognate nouns старик (an old man) and старуха (an old woman)

"That school is already very old" is not correct?

Это can be either this or that, isn't it?

Why isn't "This school already is very old" acceptable

Just another possible translation that was rejected and I think ought to be accepted, "This school is already quite old". I have reported it.

wouldn't "This is already a very old school" work?