Hey, bit confused on one point regarding the rules. It states you're allowed to use whatever tools you have the commercial license for, but also that you can only use free and open source assets (with a strong preference against them if they're not created by you during the jam). 

I've previously bought a code asset on the Unity store which aids with .fbx animation conversion into an ECS-compatible GPU animation format, which would this fall under (and would using these kinds of tools be frowned upon)?

that's fine

This is a bit unclear for me.

Is your paid tool required for building the game, or is it only used for converting .fbx to a different data type?

In another post he said "Paid tools are allowed because they produce assets you have the rights to",
so we're only allowed to use paid tools if they are only used to produce assets.

If I understood correctly if it is used to load .fbx into Unity it would be against the rules?