It appears Windows has a limit on the length of command line arguments. I thought it was an issue with the gulp plugin, but it's not just that: purescript-deprecated/gulp-purescript#36.
One option is to allow a file input to parse the commands from, or perhaps we could accept glob paths in the executables themselves - it would certainly make for a friendlier interface for people not using pulp, gulp, etc.
This is going to become a real problem for me soon, as slamdata is very close to exceeding that limit 😉