> all within a single Gradle project. [...] Groovy [...] worked with everything, though. Given that Gradle was originally designed with Apache Groovy as its on

> all within a single Gradle project. [...] Groovy [...] worked with everything, though. Given that Gradle was originally designed with Apache Groovy as its only language for writing its build config files, I'd say you should try again with the build system relevant to each language, such as SBT for Scala, Leiningen for Clojure, etc.