Happy to say I think I made big progress in the AM/PM issue today.

Fix 1:
The alarm time was translated to the locale format, but the Qt function that was used for that gave some unpredictable results. Using the US setting gave me a AM/PM result, while I had 24 hour clock actived.
I now use a different function, that seems to do a better job.

Fix 2:
The clock replacement was hardcoded on AM/PM. Not only for texts on the display, but also for checks, while the locale value can be different (in Finnish for example).
The text and checks of AM/PM are now based on the local settings.

I have done check in US, Finnish and Dutch settings.

New version can be download from the link in the first post.

@toxaris, can you also tell me if your problem is solved now?