Hello! I'll need you to be more specific about the errors you're encountering; the layered image tool is set up to work with basically any layered image declaration as it only checks the LayeredImage object after Ren'Py has already handled all the groups and such. I tested it with the following code:
layeredimage august: always "august_base" group outfit auto group eyes auto: attribute open default group eyebrows auto: attribute normal default group mouth auto: attribute smile default group glasses auto group emotion auto
and had no issues using it in the tool. These filenames have underscores in them also (august_eyebrows_frown.png and so on), so the file naming is not inherently a problem. The intention is that the tool supports as many layered image declarations as possible, which is why there are not limits listed on the itch page.

