I can't finish the quest to bring cristals to the lighthouse, what am I to do to validate it (I have the cristals).

Also that lore character told me about some obscure stuff and I wonder if it's about unlocking the blunderbuss. I still don't have it (and the tech tree is almost entirely researched, including the blunderbuss one). There's no way to read the "hint" again so I'm stuck...

Apparently it should be available from the start, never got it, not once... game is bugged then.