How am I supposed to work with Worldgen exactly? How does this tie in to Mod Datapacks?

So hi! I'm new around here, and I apologize if this is a bit of an odd question or if it's out of place but:
I'm trying to make a modpack, and I'm trying to modify the worldgen of certain modded features through Datapacks (I imagine I can ask about this here since they are still datapacks?). I think I understand the basics of worldgen functions, with a Placed Feature being the "Where it generates, conditions for generation" and the Configured feature is the actual "How it generates" for stuff like trees.
I'm trying to grab a configured feature (in this case a Walnut tree from the (Caupona Mod)[https://www.curseforge.com/minecraft/mc-mods/caupona], and try to tack it onto the generation from the (TerraFirmaCraft)[https://www.curseforge.com/minecraft/mc-mods/terrafirmacraft] mod. I thought I'd be able to use the placed feature config of their apple trees, editing them, referencing the caupona tree configured feature, and that'd work, but it seems like they aren't generating whatsoever, so I'm assuming I'm doing something wrong or I'm not quite getting how this all works
Any help would be appreciated! Been at this for a couple days and I've exhausted a lot of other resources ;-;