The second sentence at
https://help.gnome.org/users/gnome-clocks/stable/alarm-add.html or
yelp help:gnome-clocks/alarm-add

says the alarm "will go off regardless of whether Clocks is open or not."

Oh, I wish that were true! But gnome-clocks currently does not run as a background service so this does not work. See bug 735869 and bug 772819

I think the documentation here is wrong enough that it would be appropriate to either:
1) Remove the incorrect sentence in a release for all still-supported gnome-clocks versions (maybe just 3.24?)
2) Correct the string and email the translators list to ask them to update their translations before a scheduled bugfix release date a few weeks away.