To migrate from Scriptish to Greasemonkey, it is not enough to copy userscript files from scriptish_scripts to gm_scripts. Greasemonkey requires that gm_scripts/config.xml have metadata of each userscript. This script parses scripts_directory/scriptish-config.json (Scriptish counterpart to config.xml) and prints Greasemonkey's config.xml.
NOTE: This script converts just enough attributes for Greasemonkey to recognize userscripts.
$ npm install
$ node index.js scriptish-config.json > config.xml