Hello Tobi,
I cannot read the German website you quoted. But here is a brief article on Wikipedia: “Heim theory”
The description you quoted above involves an electron absorbing/emitting photons. But there is no need for such mechanisms.
– This experiment has been done on electrons and photons separately, i.e., similar interference patterns have been observed when the experiment was done with a single electron or a single photon.
– Also, whether this experiment has anything to do with consciousness is a separate issue. (It does not)
– The question of whether a photon is a particle or a wave has also been resolved: “Photons Are Particles Not Waves”