Ah, but you should look again. I know that person had lots of other errors as well but if you search for ‘localestring_get()’ 3rd hit, you will see the exact same error as in you screenshot and the explanation for that error as well.
Your latest screenshot (previous post) everything looks fine and is the same as mine (except for the different countries) but I do see one difference and do not know if it is important.
Your localectl status:
System Locale: LANG=en_US.UTF-8
My localectl status:
System Locale: LANG=en_ZA.UTF-8 LC_COLLATE=C
My /etc/locale.conf file only contains:
See if you need to add the last line and if it makes a difference.