Today i had complete some quests, right. Then, when i try to take a look at Global Quests, the "Quest Farmer" somehow stuck on that number. It didn't get updated each time I finished some quests right now ( sorry bad english ) Like from 83 quests, then I finished one quest, it keeps counting on 83 quests done.
Is this a bug or it's just like quests quota limit?

It shows that you have 93 quests completed now - does your game still show 83 when you access global quests menu?
I'll double check if there's a bug in game client as it may be not refreshing quests cache as frequently as it should, but server side it looks fine here.