It feels like this sentence should be translated as "She began to faint." Otherwise, what is the difference between vulchoH and just vul (ghaH)? We don't see any onset of the action of fainting in the English translation "she fainted."
(This was a word bank exercise, and there were no tiles using any form of "begin" or "start," so I was not able to type "She began to faint" to see whether it was accepted or not.)
Answering my own question: I see now that vul is a verb of quality meaning "to be unconscious." So vulchoH = "to faint" is completely understandable.
By way of explanation, if anyone cares, it was the first time I've encountered the word vul. The hints I saw said only "faint;" nothing about unconsciousness. And I've learned that if I leave the app on my tablet even for a few seconds to look something up (which would be my first preference) - whether on a website, in boQwI' or even in my own Word file of notes - I will lose my connection somehow, and the entire lesson I'm doing will not register. I'll have to repeat it. So I have to go by only what's available in that one screen.
Apologies for the interruption, and the ramble. I'll leave all this in the hope that maybe the explanation of the distinction between vul and vulchoH might help someone else in the future.