More context from the developer here but it’s not exactly encouraging.
the way I've set up my development environment is profoundly stupid. I think it could be used as scientific evidence that human brains can devolve. I'm not sure how to describe this... It's chaos in there.
People Playground is a technical hellscape. It's important to emphasise just how poorly this game is designed from a technical point of view.
There's nothing to be done.
It's technically impossible to properly sandbox mods in their current state.