Bugged quest, cannot proceed further

Edit 2: I created a guide that contains all the information I gathered whilst dealing with the bug, plus some more content. Hopefully, you will find it helpful. The guide is also on Steam.
Edit: I found a solution to this issue and edited the Steam Discussions post accordingly.

Hello!
As the title says, I came across a rather annoying bug which does not allow me to play further. I wrote every information about it down and posted it to Steam Discussions, so if you don't mind, please read it there via this link.
Basically, I got a quest from Jinko in Zarahakul which led me to killing the master apropir hidden in the well near to the Odd Crab's house. The problem is that the well simply disappeared, so I cannot proceed with this quest anymore.
I'm looking for any kind of help or clue.

Thanks
Spooky