Settings->Configure Desktop->Regional Settings->Formats->Region offers
"Switzerland - English (en_CH)". However, this locale is not provided by the
system as

$ locale -a | grep en_CH

comes up empty. When en_CH is selected, this leads to problems such as files
with special characters no longer being readable by KDE applications and copy
errors / files not found on ext4 disks migrated from another system.

$ locale

will show errors:

locale: Cannot set LC_CTYPE to default locale: No such file or directory
locale: Cannot set LC_MESSAGES to default locale: No such file or directory
locale: Cannot set LC_ALL to default locale: No such file or directory

locale-gen, which is available in other distros does not seem available, so
en_CH cannot be generated. Please provide en_CH and/or the tools to create it
as part of tumbleweed.

Also suggested:
- Have KDE settings trigger installation or generation of locale not already
available
- Or in the worst case have KDE settings not offer locale that are not
available