lxsession's terminal messages (lxsession --help) aren't coded to be translatable.
I'm mentioning this here as this is a thread about code that miss or brake translations.
This case would need a bit more work than the ones mentioned before as they only needed very basic changes to be fixed.
(note: I'm using lxsession from a while ago as many apps seem to be worked upon these days and translations - and other things like building or running - broke; in a few days I will try to build them again and will report the issues)