Well, that's annoying... Apparently, tsc does not install where JSweet expects it to be installed.

Maybe the installation went wrong for some reason, to you might try to remove the .jsweet.v3-node_modules directory and try again.

Otherwise, as a dirty quickfix, you may try to manually copy .jsweet.v3-node_modules/node_modules/.bin/tsc.cmd to .jsweet.v3-node_modules/tsc and see what happens.