I did take a look at the Template 12 (Portfolio, in English Portfolio [Showcase Photo] in German. I have somes notes for this template and one correction.
I would like to suggest the same suggestion I did here regarding the word Platzhaltertext for adding the word den before Platzhaltertext.
The German and English texts are talking about a plus icon at the lower left of a card. If you are meaning the Plus icon shown in the screenshot above, then the text is incorrect by its content (English and German), as this icon is in the lower middle of the (any) card.
Also, the text talks about a menu entry Karten (Cards in English), which I can not find. Is it possible, that this template was made for an older version of Sway?
Regarding the sentence ... Trauen Sie sich an Experimente ... which original in English is ... Don’t hesitate to experiment ..., I would add the word heran, so that it becomes ... Trauen Sie sich an Experimente heran ... or - imho better - translate the English text to ... Zögern Sie nicht, zu experimentieren ...
In one of the next text cards, the German text talks about the menu Layout, which I could not find too. It is also the case in the English text. So, not a translation error, but may be confusing the user.