Glad to hear it worked and I could help^^
Normally you need to be in mermaid form and then speak to her, this will trigger the quest. It isn't enought just to have unlocked it you also need to be in that form. I think you till should be able to trigger it if you want to see the dialogue, it should not softlock your game but will remove your exp shards and teammates, so better spend them before trying it since you already completed the quest.
It also should now be impossible to get into the same softlock as you did as well.
I see, then I probaly only forgot to disable it when leaving the area through teleportation, will fix that as well, thanks for noticing!