Rationale: Kleros offers great insights about its 'crowdsourced' lists via https://blog.kleros.io. Only, I could not find out how big the community of early adopters is.
The Graph: Working with the Graph was a really smooth process once it became clear that I could add custom entities and relationships.
Challenge: The most challenging part was understanding the source code of the token list contract ArbitrableTokenList.sol.
Findings at the time of writing: For the curated token list, there are 46 active users that added or removed tokens, or challenged submissions. 21 users have submitted 1 token to the list, and 26 users 2 or more tokens.