https://gerrit.wikimedia.org/r/#/c/154374/ changes the special page to use FormSpecialPage but the submit text was not set to old message 'randomincategory-selectcategory-submit'. This is no problem in english because it is "Submit", but the default used submit text 'htmlform-submit' defaults to "Speichern" (save) in german translation. That is misleading on this special page. Other languages have similar problems.