This image shows the supposed location of this note according to StreetComplete. There is a sign "Römische Tempelanlage" at the street but it points to the opposite side of the the street from this note.

In the second image i'm pointing towards the location of the note and where the first image was taken. We also checked the small hill about 100m from the note and could not find any remains of a roman structure.

Attached photo(s):
https://westnordost.de/p/239129.jpg
https://westnordost.de/p/239130.jpg