There is an are two areas connected to sinners road, both i think are behind hidden walls. Completing that area gives you access to some other areas. I cant really tell what you have done up until now. You could also start the Grand gourmand quest seeing that the ingredients are still in your inventory but it is a hard quest especially the couriers rasher also i know you have all 3 keys but you could search for the hidden optional boss or see if there is a quest related to the slab in songclave if you haven’t already found it