https://en.wikipedia.org/wiki/Palmar_grasp_reflex does not have a German translation.
The term Klammerreflex is the correct term here; German wikipedia just doesn't have an article for it.
Knowing wikipedia in at least one other language gives a lot of perspective. Some language-based communities are so small that most articles get hijacked by a few people with a particular agenda. Not German though, no complaints there.