Thank you! I'm interested on the shadow issue, what do you mean exactly? In the initial versions of the game, the sail was semi-transparent and I was thinking of adding an option in the menu to make it like that, do you think that might solve the problem?
Viewing post in Paraploimos Emporion jam comments

I think it would. It could also help with more ambient light, softer shadows or softer diffraction on the sail, not sure what is possible. Or maybe just change the perspective a little, peek out below the sail maybe.
The screenshot above shows what I had in mind: Since you need to have the sail down, there always is this high-contrast flickering shape taking most of the room on your screen.
But it's just a small thing really.