I'd like to be able to configure the height at which a player can gain speed when flying, by modifying this 64 value here with a new key value pair in the config file.

https://github.com/CammiePone/Icarus/blob/a4686a51489c435dc29dbd2188109305f73c2661/src/main/java/dev/cammiescorner/icarus/core/mixins/PlayerEntityMixin.java#L34-L35

yea, i can add that