Just going off of what all I see needs to be done in reference viewer for PrimalItemResource_ChitinPaste (cemeting paste), try these steps (moving all new files to your mod folder, compiling, and saving along the way - order is not terribly important):
Make sure the new PrimalItemResource_ChitinPaste_Child replaces the old in PrimalGameData_BP_Child in master item list.
Scroll down to remap resources and remap PrimalItemResource_ChitinPaste to your new PrimalItemResource_ChitinPaste_Child.
Scroll back up and check your engram list has your new EngramEntry_ChitinPaste_child instead of the old.
Make sure your EngramEntry_ChitinPaste_child references your new PrimalItemResource_ChitinPaste_Child.
Duplicate (not make a child unless you know a workaround to the first photo in this post: GenericMod Questions - ARK: Survival Evolved - Epic Developer Community Forums ) the MortarAndPestle blueprint, go to components, click PrimalInventoryBP_MortarAndPestle, and change the chitin paste reference to your new PrimalItemResource_ChitinPaste_Child.
Open TestGameMode_Child and change Player Controller Class to be your new PlayerControllerBlueprint_Child.
Open PlayerControllerBlueprint_Child and change Structure Placer Class to be your new StructurePlacerBlueprint_Child.
Open StructurePlacerBlueprint_Child and add an element to the Placeable Structures list to be your new MortarAndPestle duplicate.
Open EngramEntry_MortarAndPestle_Child and change Blue Print Entry to be your new PrimalItemStructure_MortarAndPestle duplicate.
Open PrimalItemStructure_MortarAndPestle_Child, make any changes you wished to do, change Structure to Build to be your new MortarAndPestle duplicate.
Ensure your map loads your new PrimalGameData_BP_Child and TestGameMode_Childblueprints.
If all else fails just add an entry to the bottom of the master item list and put the old PrimalItemResource_ChitinPaste there and be sure to test to make sure the item used in game is your modified item (may want to add something to identify it in descriptions or something.
Hope this helps, but I cant guarantee this is still everything that needs to be done (since I wrote this off the top of my head rather than performing each step personally).
I’ve tried doing it 3x now. I can replace Mortar and Pestle and it will work. But the second I try to replace Chittin Paste it will crash. The problem is I expect to do with the fact that I’m editing material that is being used for crafting. Where as all you are doing is replacing crafted material. Something tells me there is control not exposed, or that I dont know about or its bugged. I’m waiting for a friendly person to check my files and well see later. So far I cant get it to work.