Gamification Specialist here :) - Worked in SAAS gamification platforms,

Ensure that the achievements aka rules, are also able to 'communicate' with one another through points transfer, allowing you to use them to create economy models.

AKA 1 achievement on one promo can give progression in another promotion independent, so there are different ways to connect the achievements rather than just being a linear multi-level achievements,

Sounds like a fun project maybe can help with some of the scope :)