This is the Tmbol's AI-slop texture replacement plugin.
To use this plugin, simply drop the textures you want to get replaced into the "Textures" folder beside the plugins's dll. The format (png/jpg), name and dimensions of the image must match otherwise the AI code may delete your system32 folder.
Some images like most item icons require transparency. Make sure they are transparent, or else.
You have to get the names of your textures from an Unity assets inspector/viewer like UABEA.
Open the inspector of your choice and point it towards <your game install dir>\PEAK_Data\resources.assets
(for example: C:\Program Files (x86)\Steam\steamapps\common\PEAK\PEAK_Data\resources.assets)
Then, simply look for name of the texture you want to edit (for PEAK it's usually not garbled or anything), and ideally export it and use it as a canvas for a clean workflow.