I honestly don't think there are such things as bad, good, and true endings. This was very clear in Dark Souls, but somehow the addition of a third ending got everyone back in the classic videogame mindset, but it's not the case at all. There's no canon ending, no happy ending and no bad ending, just different outcomes (my favorite is the submit ending, after all).
About Eileen and Djura submiting to Gehrman, I think it's quite unlikely. Djura because IIRC his equipment just says he basically gave up on the hunt, so if he abandoned the hunt to take care of Old Yharnam, he couldn't have come to the end of it, after all, his big revelation is the obvious "beasts were humans once". Eileen definitely gets more complicated, but I don't think Gehrman is just flat out wrong in the most important part of his quest, if he says you'll forget the dream, I'm inclined to believe.