Could you explain what is broken in the current version of Kenney Studio? As said, we're preparing a last update and it would be fantastic to get all issues out. You've spent $19.95 to get access to our software (you still have, and will always have access to it) plus three years of updates next to getting a large discount on our unrelated new software package.
Kenney Studio didn't allow users to create their own objects, this was also never advertised. Asset Forge can and we've written a guide for it.