How do you translate this token in the daily and weekly digest email notification body?

The following steps should take you to the translation for this token:

Pencil Icon > Translation > (Enter 'Digest' into Filter) > Select Email Digest Tokens > Scroll down to' ApplicationNewContentCount'

Thank you! However, if I select that token, the text is correct:

But seeing the email (production, not test email), I can see a different text (see yellow marked text in image below):

That specific text 'discussions' I am not able to find anywhere in the translation part of the admin panel...

I would suggest that you submit this as a support case, it's going to need a bit of digging into.