/timername -e is executing the associated command of the timer by actually triggering the timer, changing the setting of the timer. It 'sets' the number of second left before the timer triggers to 0 which as a result decrease the number of repetition of the timer.
This behavior came as a surprise to me, the help file is also not mentioning this.

If this is a bug but can't be fixed because of backward comp, please consider adding /timer -eN with N = 0 (default) for the current behavior and N = 1 for just executing the command without changing the settings of the timer. Please also update the help file to be explicit about this.

Thanks for your bug report. This is behaving as it should. The purpose of -e is to execute the timer. The help file description has been changed to match versions.txt:

Ok, thanks.