Hi! I've got a crash while testing your mod in Factorio 2 without Space Age:

   1.642 Failed to load mods: __shrekported__/prototypes/shrek_character.lua:40: attempt to index field 'level4' (a nil value)
stack traceback:
  __shrekported__/prototypes/shrek_character.lua:40: in main chunk
  [C]: in function 'require'
  __shrekported__/data-final-fixes.lua:2: in main chunk

EDIT: The crash occurred when both your mod and Voxelll's Shrek fix 2.0 were active. Adding a conflict against that mod would prevent the crash.

While I'm at it: You can simplify your mod considerably by delegating the work of copying properties from/to the default character to my helper mod. This way, if I ever have to change the way it's working, you won't have to update it on your end. (Fun fact: You're already using a kind of stand-alone version of my helper mod. The original "Shrek" mod was based on the original "Gear Girl" mod for which I provided the original copy/replace code – which unfortunately never was updated and so some mods replicated the obsolete version.)

Incompatibility has been added, but I will add the use of libraries from your mod later (maybe)

Thanks! :-)