Yes, there is an official walkthrough among the game downloads. Right now, it's the 6th option from the bottom. Though if you'd like to play alongside the walkthrough, I would recommend you a walkthrough mod for convenience.
The ending of the latest game version is the same regardless of your choices up to that point.
There is often leeway for mistakes, though some individual mistakes can ruin a path on their own. The bathroom lewd is not mandatory for Dalia's path. If you got to the end of 0.4 with her path intact, you're probably fine.
If you want to be 100% safe, you should fully replay the game alongside a walkthrough because future consequences & affection point thresholds are still unknowable. Some people fully replay Eternum with each new update!
