what does the typo look like? if I may ask
That's not something I can really answer because the typo is not consistent across files.
Basically every time you get a "Failed to Load image" Error while playing with P-Cup you need to check the name the game is asking for, then WITHOUT CLOSING THE GAME go to the path where the image is supposed to be, and find the image by manually going through all the files using the real file name from the error as your only hint.
The good part is that the files, at least so far into my playthrough, are all there, and the PCup files are clearly labeled, hell the whole folder is clearly labeled by Breast Size, NPC, position, and even variant.
Anyway once you find the file, all you gotta do is type the name of the file without changing the format since the error asks for a PNG, ignore that since the game uses RPGM's image file format. Once you do that you hit retry and the game will resume like nothing ever happened.
Honestly all this hunt is not worth it, i do it because I am impatient and wanted to try the DLC before it's actually finished, but i'd recommend everyone else to just wait for the official release.