This is something I just completely don't understand, picking a undiscovered joker during a challenge run does not reveal it for the purpose of your collection. (Yes, I did buy/pick up, not just see)
And having mostly the challenge modes left just stops me from filling in the collection whatsoever.
#Jokers discovered in challenge runs not adding to collection
abstract plaza
heady python
afaic challenge runs won't unlock any collection or achievement, perhaps this is by design :(