itch.io

The person who found no indication of keys would then have found a steam key claim that simply says "There are no keys available at this time, try again later" when clicking the button, instead of nothing. Additionally, attempting to buy the bundle currently clearly says no steam keys, which it didn't before : 

But again, fair concern, you're right to wait, and it's rather unfortunate of itch.io to make the mistake and then not reply to you.
Good luck with this! And with your future games, you make pretty cool stuff =)

Additionally, here's a discussion where someone got the bundle later mentions not finding any steam keys. https://www.steamgifts.com/discussion/z00yf/itchiosteam-bundle-charity-bundle-no...  (some other people in the thread mention not getting steam keys with the purchase as well)
Not official sources and all, but hopefully all this allays your troubles somewhat. =)
Hope you get an official reply soon too.

Well the bundle used to say "16 steam keys included" and listed them; it doesn't say that anymore and has no steam keys listed. Their docs also mention that they generally turn it off for charity bundles, meaning this was most likely an accident.  https://itch.io/docs/creators/bundles#hosting-a-charity-bundle .
"Generally, for larger bundles priced lower, we will disable all access to External (Steam) keys to prevent participants from having to generate an unrealistic number of keys. "

Admittedly the part about claims staying for people who bought it is conjecture from reddit discussions & some people here complaining about not being able to generate steam keys from their purchase https://itch.io/t/5910207/cant-find-my-steam-keys-anywhere#post-15462771 and from vague memory of a previous instance where that happened.

Itch did grand some on accident and removed it for further purchases, but the claim stayed for people who bought it while it was configured wrongly.
I'd assume Steam ain't gonna force you to give away your game for free because of, essentially, a pricing error. I mean, those happen regularly, get corrected, and none of those game thereafter were as cheap on steam as during pricing errors.
But the concern is understandable. Sorry to hear you're having to deal with this!