How do I go back to complete a treasure collection?

In my challenges I still have to complete the folding fan series because my stuff got raided during the arena event and I kept going on and collected an completed a lot more treasure collections how can I go back and get the fans so I can complete them?

just go back to the world with the fans. I think someone already asked this question and I believe the answer was that if you get to high of a lvl you cant fight the ppl or get the treasure anymore. Well try goin back to the world that gave it to you and if that dont work then you cant finish it then. Sucks but it really doesnt matter if you go back to finish the fans or not, you get a weak prize for them and the ppl that you fight barely gives you enough exp at all. So its not really worth it in my opinion.

Here is the thread:
https://ninjaroyale.forumotion.com/t77-glitch-with-treasures

Yeah, I'm lvl 431 right now and I can't complete my quest for the Houses... I spent 99 energy trying... and its just not worth the effort to get 10k coins

anyone know what world is the houses??

Not really sure, but I'd just move on. The rewards are bad, and you don't need to complete them