So, I solved it! For any other beginners out there who have knowledge gaps that would lead to this struggle, here is the solution:
In the character’s skeletal mesh window, go to the curves tab, then add curves for every ARKit expression, named exactly the same as the morph target it corresponds to. In the ‘Type’ column, it has two options by default covered by a red X, hovering over them will reveal what they are: ‘Morph Target’ and ‘Material’, click the morph target option for each curve and it will turn into a green check mark. Save the skeletal mesh, then test the livelink motion capture again, it should now work.
Part of why this was something I didn’t try right away was because the original model I bought did not have any curves, it just was plug and go. And also, every resource I found that taught how to set up characters with blendshapes in blender and import them to Unreal to use with live link never made mention of curves. Literally, I did this on a whim as a hail mary lol! I don’t know why this is the solution or why making blendshapes with faceit was causing this and doing it the regular way didn’t cause it, perhaps users more knowledgeable than I can answer that, I am very curious.