Thanks to the glorious thing that is deferred registry, it's currently completely impossible for modders to use custom effect instances in their food items, as non-vanilla MobEffects have not yet been registered by the time the FoodProperties builder needs them (see KubeJS-Mods/KubeJS#151 for an example)

Forge fixes this by patching FoodProperties to use Supplier instead, such that the effects can be resolved after registry has finished, but obviously, we unfortunately don't have access to that in common, so we will definitely need to fix this up ourselves