sorry, misread the bit about the ceremony. No, you can't go back currently if you chose to leave via need2go, though whether you should be able to come back, I don't quite know. In regards to the purified incubi draft still creating a dick, that's a bug, and will need to be looked at.Fought them...? I checked two of the three "submit" options, Got2Go and Keep Name, Got2Go didn't put the place on the Places list.
The fact that the PC can submit to the Elven transformation from the tree and then still use a purified incubi draft proves the tree does nothing to prevent later growth of a dick. I don't remember anything about the tree providing for them aside from shelter, they still produce their own weapons, hunt their own food, and defend themselves when they do encounter hostilities. Just, similar to the kangaroo clan, they have kept to themselves, rarely speaking with those outside, and only when the outsiders come near.
After going through the submit>keep name sequence, I at least found out on return they mentioned curing the tree, so there is something to do in that route, but it's unfortunate that Submit>Got2Go does not (or at the very least, makes it very difficult to get back for it, since Forest(I) never popped it up even after a couple more weeks)
And I should have clarified. Bt "providing for them" I really should have instead stated "kept their souls". Yes, they do still need to harvest, hunt, and create their own gear.
If you want an answer faster, you're welcome to join the discord instead.