I'm just starting out with wanderer's friend, and it looks pretty fun.
I think I've found a bug, though. I did the "Clean feathers" reaction starting with a Turkey gobbler feather, and when I was done I had both the turkey gobbler feather and a turkey feather (which seems to function the same as leather). I was then able to do it again and still had the turkey gobbler feather and now had two turkey feathers. It looks like the original feather isn't being used up, so I can make an infinite number of turkey feather leathers.
As an aside, I'm not sure I understand how one can use feathers as a leather replacement. Even if it's fixed to use up the original feather, does this reaction really make sense?
EDIT: Another bug. I made some pants from some leather sewn with some dried guts thread and they ended up being called "dried gut trousers". This one I can see a fix for. In reaction_wanderer.txt, in the [REACTION:SEW_CLOTH_PANTS_ADV] it says:
[PRODUCT:100:1:PANTS:ITEM_PANTS_PANTS:GET_MATERIAL_FROM_REAGENT:A:NONE]
I think that should be:
[PRODUCT:100:1:PANTS:ITEM_PANTS_PANTS:GET_MATERIAL_FROM_REAGENT:B:NONE]
I also spotted the bug in the feather cleaning reaction. In reaction_wanderer_materials.txt, the reaction is:
[REACTION:CLEAN_FEATHERS_ADV]
[NAME:clean feathers]
[ADVENTURE_MODE_ENABLED]
[REAGENT:A:1:NONE:NONE:NONE:NONE][USE_BODY_COMPONENT][UNROTTEN][REACTION_CLASS:FEATHER]
REAGENT:B:1:TOOL:ITEM_TOOL_COMB:NONE:NONE][PRESERVE_REAGENT]
[PRODUCT:100:1:SKIN_TANNED:NONE:GET_MATERIAL_FROM_REAGENT:A:NONE]
[SKILL:TANNER]
There's a missing [ on the reagent B line. That's making it not require the comb, and also preserve reagent A.