For the record, finally I got it to work, too.
But I think some explanation is required here.
I ran into this python-script-not-running-issue because I had the assumption that python was preinstalled or at least would be activated by applying developer-mode... But unfortunately it's not. Thanks to thedead1440 for the enlightenment!

So for everybody else clueless like me, install Python first by I really think it can't hurt to give info like this in the first post or a project page, if existent like in this case.
I was close to losing my nerve. As if being a Linux-n00b wasn't enough...
Anyway, thanks for this great app and the python-feature.

Feature request:
- Show if Bluetooth is activated (in case you have forgotten it's enabled, which happens quite often to me)
- Show clock-alerts
- Show flight-mode if activated