I've added a list of the post categories. There's a problem - it sorts by English, so categories starting with "ö" is in the middle of the list. My initial search for a solution has told me that we either need to install a plugin or edit the theme to fix this.

Another thing this reveals is that we've been inconsistent with upper/lower-case naming of categories :/

In T227326#5320196, @Alicia_Fagerving_WMSE wrote:

Another thing this reveals is that we've been inconsistent with upper/lower-case naming of categories :/

:) I've renamed them now - there weren't that many starting with a lower case, so I changed them to upper case.