It may need 10, I don't remember (tho you def don't need 15). Etheria respawns only if you sleep on Sunday alone. Quests mostly tell enough information, but sometimes there's a specific time when it should be triggered. Also there are some dev tools in that cristal in the bedroom. And the last resort, you can start a new game and either replay it or start from 0.89, there's still quite a lot of content in-between, but you probably can watch all of it in event theater. Hope something here helps.
I will try 10 Etheria. I do not know how much I need because I do not have a "main quest" currently. I checked the Wiki and it only said "while she is working" which I am asuming means "when the work option is available". I tried reverting back to 0.94 but I was not able to download a previous version. I started playing this game at version 0.95