> +       ;; FIXME: tests are not run
> +       #:test-dir "src/test"

Why not?

> +       #:phases
> +       (modify-phases %standard-phases
> +         (add-before 'configure 'chdir
> +           (lambda _
> +             (chdir "subprojects/groovy-console")))

#t

> +         (add-before 'build 'copy-resources
> +           (lambda _
> +             (copy-recursively "src/main/resources" "build/classes")))

#t

LGTM!