I would use a more introductory message, like:

````rst
When maintaining a bundle, you may use or remove the usage of a translation
message without updating all message catalogues. The ``translation:debug``
command helps you finding these missing or unused translation messages for a
given locale. It shows you a table with the result when translating the
message in the given locale and the result when the fallback would be used. On
top of that, it also shows you when the translation is the same as the
fallback translation (this could indicate that the message was not correctly
translated).
````