I tried knocking out the 4 masks. Now, after beating Ethel and Long Resting, they're jist gone. No talking to them.
Im assuming they'll bring these characters back in somewhere, maybe in Baldurs Gate, but who knows.
As for Eds siblings alerting the camp, first playthrough or not, if you spared them and they told all their cultist friends about it, that's on the player.
I also love that aspect of the game and want more of it. Actions with different consequences. I also love that there are multiple ways to continue the story. So what? You can't just waltz into camp? [spoiler]Go to Risen Road, near the mountain pass, jump across, sneak in from the cliffs. Or, sneak in through the Underdark via Ethel's lair or the Whispering Depths.[spoiler] There are so many paths. After EA, you will even be able to skip the goblin camp altogether of you want.
So no. Don't take that away please. That kind of thing makes replaying SO much more fun. If anything, I want more. Use too many long rests, Tieflings get kicked out and the grove is sealed. Goblins attack. Time to save the Tieflings OUTSIDE the grove. Stuff like that would make the game even more awesome.