I have a system which uses mixed language settings of English and German. All Region & Language settings under KDE are set to “British English”. My keyboard uses a German layout.
Pamac, when using to install the firefox-pwa package from the AUR presents this:
$ pamac install firefox-pwa
Warning: firefox-pwa ist nur im AUR verfügbar
Preparing...
Checking firefox-pwa dependencies...
Resolving dependencies...
Checking inter-conflicts...
To install (1):
rust 1:1.74.0-1 (Required By: firefox-pwa) extra 89,3 MB
To build (1):
firefox-pwa 2.9.0-1 AUR
To remove (1):
firefox-pwa-bin 2.9.0-1 (Conflicts With: firefox-pwa)
Total download size: 89,3 MB
Total installed size: 471,6 MB
Total removed size: 27,0 MB
Edit build files : [e]
Transaktion durchführen ? [e/j/N]
Only the last line is suddenly German, presenting the options e/J/N, but accepts only the English e, y and n. (‘j’ does nothing).
Verify the files has expected configuration
- ~/.config/plasma-localerc
- /etc/locale.conf
Also check /etc/locale.gen (bottom of file) and that locales are generated correct using locale-gen.
plasma-localerc:
[Formats]
LANG=en_GB.UTF-8
[Translations]
LANGUAGE=en_GB:de
locale.conf:
LANG=en_GB.UTF-8
LC_ADDRESS=de_DE.UTF-8
LC_IDENTIFICATION=de_DE.UTF-8
LC_MEASUREMENT=de_DE.UTF-8
LC_MONETARY=de_DE.UTF-8
LC_NAME=de_DE.UTF-8
LC_NUMERIC=de_DE.UTF-8
LC_PAPER=de_DE.UTF-8
LC_TELEPHONE=de_DE.UTF-8
LC_TIME=de_DE.UTF-8
locale.gen (bottom):
###
#
# Locales enabled by Calamares
de_DE.UTF-8 UTF-8
en_GB.UTF-8 UTF-8
en_US.UTF-8 UTF-8
I am not annoyed by the German selection line (which should not happen, if the rest of pamac uses english), but especially the presentation of ‘j’ for yes, but accepting the English ‘y’ 
Konsole is controlled by Plasma - try removing this section
I only removed the :de and now it works. This is weird behaviour.
The only issue left over now is a new error message from bsdtar (‘bsdtar: Failed to set default locale’)
Weird. All that I have changed is removing that ‘:de’ from ~/.config/plasma-localerc.
Full output:
pamac install firefox-pwa
Warning: firefox-pwa is only available from AUR
Preparing...
Checking firefox-pwa dependencies...
bsdtar: Failed to set default locale
Resolving dependencies...
Checking inter-conflicts...
To install (1):
rust 1:1.74.0-1 (Required By: firefox-pwa) extra 89.3 MB
To build (1):
firefox-pwa 2.9.0-1 AUR
To remove (1):
firefox-pwa-bin 2.9.0-1 (Conflicts With: firefox-pwa)
Total download size: 89.3 MB
Total installed size: 471.6 MB
Total removed size: 27.0 MB
Edit build files : [e]
Apply transaction ? [e/y/N]
Likely because you didn’t run locale-gen after adding en_GB - try running
sudo locale-gen