Flask Babel - 'translations/de/LC_MESSAGES/messages.po' is marked as fuzzy, skipping
You can force pybabel compile to compile messages marked as fuzzy with the -f (or --use-fuzzy) command line switch:
pybabel compile -f -d translations'Fuzzy' messages are marked with a #, fuzzy line above the msgid line, and are the result of a merge where a message is deemed slightly changed from the previous version. A message marked as fuzzy is supposed to be looked at by a human to make sure the translation doesn't need updating, after which the human translator removes that flag.
As pybabel said: The catalog itself was marked as "fuzzy" (6th line). If you remove that line, you don't need the 'force' option.