The achievement types that do give rewards need to be documented. What we know right now:
- The game knows what achievements should get what rewards (so we can extract this somehow)
- The game doesn't tell the server which rewards it is handing out, but it does tell us the achievement ID for achievements that were cleared, so if we can extract this reward data from the game we will be set.
Right now yell achievement rewards are given at yell rank 20 and 80 since those milestones give member cards and having access to those is quite nice.