I doubt the people who find it difficult to just control will be writing any scripts. Writing scripts—any kind of scripts, for anything, even quite simple ones—requires certain way of technical thinking they don’t have. So the non-technical users will mainly scourge forums for useful enhancements they could use. That is the case you have to keep simple.
However, the people capable of writing the scripts should also be able to run some kind of simple tool to compile or preprocess the scripts. It would be making it slightly harder for them to share their creations, but if that’s what it takes to fit the scripts into the device, it should work fine. So I think you shouldn’t completely rule compilation or preprocessing out.
Note that since the device is too small to fit in even a rather small interpreter like Lua, the scripts it will be able to handle also won’t be very big. I expect usually one, at most a couple of files. That does not need dependency management or complex build system and such. Just a tool that you run and it will find all sources in a given folder and produce corresponding binaries to be copied over to the device.