I am now unable to reproduce this.
When first investigating this issue I found that "warteschlangen" had a spurious ':' character at the end in the translation file. I corrected that and retested.
Checking the current 2.4.4 snapshots I find that there is no longer a colon at the end of the word, so I have no idea how the OP is still seeing the issue.
Please check your pfSense version, and then run this test:
cd /usr/local/share/locale
grep -ri warteschlangen *
This is the output I obtain, which shows no extra ':'
de_DE/LC_MESSAGES/pfSense.po:"entfernen Sie alle Warteschlangen zu dieser Schnittstelle um fortzufahren."
de_DE/LC_MESSAGES/pfSense.po:msgstr "Warteschlangen"
de_DE/LC_MESSAGES/pfSense.po:msgstr "Warteschlangen Status"
de_DE/LC_MESSAGES/pfSense.po:msgstr "Status-Warteschlangen"
de_DE/LC_MESSAGES/pfSense.po:"Pipe mit Bandbreite, Verzögerung, Packetverlust und Warteschlangengröße wie "
de_DE/LC_MESSAGES/pfSense.po:"Für Warteschlangen unter derselben übergeordneten Ressource bestimmt dies "
de_DE/LC_MESSAGES/pfSense.po:msgstr "Generiere ALTQ Warteschlangen"
Binary file de_DE/LC_MESSAGES/pfSense.mo matches