Should the message start with "Server doesn't recognize your mygpo account" or similar, and then offer the advice about username not email?

The message should probably also be a single translatable string instead of two.

The message could use some punctuation and tweaks.

Could not find your device.

Check login is a username (not email)
and the device name matches one in your account.

We can run make messages after merging, so anything you didn't manually modify shouldn't be included in the commit.

I just tested this and the """ quoting not only indents the strings in translations but also on the dialog. It would be better to wrap each line in a string.

                    message = _(
                        'Could not find your device.\n'
                        '\n'
                        'Check login is a username (not an email)\n'
                        'and that the device name matches one in your account.'
                    )

I have never used gpodder.net, do you know if this message happens anywhere other than when clicking the replace on server button on the gpodder.net preferences page?

This is only for error handling on the set_subscriptions api call, and only an email / bad deviceid can cause this

Thank you.