Redefine player activity level?

Can you redefine player activity levels via mod?
I’ve tried to use same approach as with items/recipes, i.e. copying related activity definition from player_activities.json into my mod.json and changing values, but i get " Redefinition of ACT_DISASSEMBLE" error during mod load.

And another slightly-related question: am i correct to assume that any recipe that has “activity_level”: fake or no “activity_level” set at all defaults to player activity “ACT_CRAFT” (which is moderate exercise)?