After spending the last 4 hours trying to figure out why only .groovy's seem to be working on any of the current bots compatible with 07 scape, I have finally found a fix.
After downloading the .jar for a local script, simply change the extension to .zip, and then back to .jar again.
The reason this works is because when a .jar is compiled on a windows computer it isn't always recognizable by the mac operating system. Therefore when one turns it into a .zip and then into a mac based jar everything works fine and you can simply drop it into the script folder.
I hope this helps, please spread the word!