Glad you enjoyed it.
I was going to add a drawing showing what the fountain item was, but totally forgot about it. I was going to reference the Channeling Stone from Silent Hill 2. But the glow shape was indeed based on the Undertale save point.
About the dialogue problems, the Dialogic addon has a lot of problems that I couldn't fix, nor I had the capability to create a system on my own.
As far as I had tested, one of the problems was that mashing the interact button and starting a conversation before the window animation ended caused the new window to go invisible for the first dialogue line.
Maybe using an await instruction on the source code of the animation or adding a wait command at the end of every dialogue could fix that, I will take a look at it later.