In general, Repentogon is an API extension mod, that adds over 800 new functions for modders to use for their own mods. Most of which are impossible to achieve with the default modding api of the game. Here is the website: https://repentogon.com/

For example in EID, we use repentogon to have a feature that tells the player, if they need to collect an item for the progress on the collection page. We also use it to add item descriptions into the "Collection" page on the stats menu, 100% accurate Bag of crafting recipe calculation, Spoiler avoidance based on achievements and other gameplay statistics, and some other improvements.