I am not sure to understand what message you write about, however all
messages seem to be translatable inside dedicated aggregate group thanks to
I mean on a message in a big yellow box which says "Translation admins:
Please do not mark this page for translation while it's still a draft. The
content of the newsletter is simplified before being marked for
translation, and marking it for translation before that's done increases
the work of volunteer translators. Thank you!".
It isn't available on page for #43 now, but in #44 it is.
And template isn't translatable, as when I open URL which you provided me,
it shows that everything is translated already.
If template is translatable, then it should be added into the group.