My system main and only language is set to “French fr_FR”, and since upgrade to 42.3, the login screen shows up in english, login menu too. Never had that problem on this system, set up as 13.1 in 2013 and successively upgraded as new versions are available.
try to switch to a different language in yast>language, confirm, let yast delete the rpms of your language and install those of the other lang. Then do it again, this time switching back to your preferred language. I had this problem after a network install of tumbleweed.
I switched to sddm, and everything goes right. I don’t understand : my desktop had no problems, switched to sddm when it had to happen in the continuously process of upgrading from 13.1 to 42.2 then Tumbleweed, my laptop stayed stuck with kdm from 13.1 to 42.3.
I had also noticed on the laptop that I had the params in the kernel command line repeated four times as if every upgrade had added his own set…
Well, the problem here likely was that we don’t ship translations for kdm anymore… (sorry for not thinking about that earlier )
kdm is dead upstream since two years, and the translations have been removed from kde-l10n (upstream) as well about a year ago.
If you are fine with sddm or any other displaymanager, use that.