Hi, Patrick.
Regarding the `bindPassword` element in configuration json file - I believe you need to encode your clear-text password first before placing it there, like this: `# /opt/gluu/bin/encode.py YOUR_PASS_IN_CLEARTEXT`. I think our docs miss this step.
Answering your question - to troubleshoot custom auth script you should check logs under `/opt/gluu/jetty/oxauth/logs/`, specifically `oxauth_script.log` and `oxauth.log`, there should be some clues at least.
Please try to encode your passwords as specified above, meanwhile I'll try to check basic multi-auth script myself, and will get back to you.