If you're planning to make something bigger (heh) as a team, I'll definitely suggest investing more time in learning the coding side. Renpy is good for basic things but beyond very basic customization, it can get frustrating real quick. Having the artist know bits and pieces about it is also helpful since they will know exactly what kind of asset is required.
It's getting very technical here, but for example, I can see you have the whole JJ's full body sprites variants, and then there are resized versions. You can simplify things by using layered images. Your workflow will be more streamlined.