In my village, I try to reset my villagers trades by getting rid of their workblocks. They stay with the same trades and I can still trade with them despite them not having workblocks. I don't know if this is intentional but I have a feeling it's not. Note: I did trade with the villagers but only once or twice with my librarians but I completely uplevelled my fletchers to master. I don't know if this will help but if you could help it would be nice. Thanks.