The code runner first tries evaluation as a Groovy image, if groovy fails then tries it as a Scala image, if scala fails then tries it as a Nashorn image. Given that Javascript is more common than Scala and Scala more common than Groovy (http://www.tiobe.com/index.php/content/paperinfo/tpci/index....), perhaps you should reorder the evaluation attempts to get the most probable language first. Heck, Groovy's only really used in Grails nowadays so you could even drop it completely or swap it for Clojure.
as a matter of fact I code a lot in groovy, with no grails, but spring, but I hear you. There's a request to add support for hashtags with language choice https://github.com/softwaremill/jvmbot/issues/1 so it might solve your issue. Adding support for Clojure is more then welcome ;-)