I've noticed Grimm has changed quite a bit over the past few series & not in a good way.
This episode was the worse so far, not checking details of the history or Runes details & a wide & wholly incorrectly connection to Celtic history.
To top it all off, Grimm writers/researchers were good at languages especially German but to call Rosalee translation as 'Irish'; It was more like gibberish, they didn't even try at Celtic or Latin, horrific :(