I don't know if this is within the scope of the mod, or even possible, but it's something that would be REALLY cool imo. Would allow other modders to add their own compat if the generated compat isn't great, and could be really sick for modpacks.
I think it would probably work best if there were 2 json folders: 1 for requested items and 1 for spread. Requested items could have fields for normal and final items, and spread could have fields for top block, below-surface block, and maybe a few blocks that could spawn above the ground (like Shriekers, Sensors, etc. in Sculk blooms).
Conversion Crucibles are already awesome as hell but I just figured I might as well propose this idea as something that could make them even better!