Awesome! This squeezed the single cart version of Mot's Grand Prix down by 15%, enough to fit in a whole 4th track. Thanks for sharing this.
(I always have to untick "Other identifiers" for though. Must be something about my coding style...)
I've narrowed down a couple of issues.
It appears to be renaming words inside multi-line strings (using [[ ]]):
this=5 function that() print("hi") end string=[[ this and that ]]
And ultra-compact mode appears to have difficulty with the short-hand "if" syntax:
function compare(n) if(n>10)return "big" return "small" end print("15 is "..compare(15))