I don’t have any references handy, but I have anecdotal evidence that supports the idea of the super mundane being affected by the viewer.

Essentially all of the non-divinatory mysticism of the Near East, Europe and Northern Africa requires the practitioner to be ritually clean; physically, mentally, and spiritually. A key element in achieving that state is often isolation from the mundane world, with the duration of that isolation being directly proportional to the power of the magical working being performed. If the intent is to directly communicate with or control a super mundane entity the requirements for isolation can get pretty extreme; spending 40 days in the wilderness with extended periods of fasting and stuff like that.

In addition to isolation during preparation, secrecy during the working is explicitly required. I can’t think of any examples where multiple people are prohibited from participating in a working. But the requirements for achieving the necessary level of purity often prohibit speech and combined with the other requirements it would be extremely problematic to involve multiple people.

Problematic ranging from the magic simply not working to the summoned being obliterating or possessing the practitioner. So the stakes are pretty high to get it right. The overall implication is that if you want to summon angels or demons or bend the very fabric of existence it’s not a party trick. It’s something done by an individual, in isolation.

There are plenty of less esoteric mystic examples of super mundane practices requiring isolation. In Judaism only the High Priest could enter the Holy of Holies and speak to G-d on the Mercy Seat of the Ark of the Covenant. Elijah carried the dead body of Zarephath’s son upstairs, apart from the others, and brought him back to life. Elisha did something similar in Shunem where he laid on top of a dead boy and after some time apart from the others he took the now living boy to his mother. Peter did the same with Tabitha in Joppa where he explicitly cleared the room and brought her back to life.

Conversely, there are many examples of public displays of super mundane acts in the Bible. The feeding of the 5,000, resurrections, casting out of evil spirits and all kinds of things In Exodus. The Rod of Aaron turning into a snake and eating the snake conjured by Pharaoh’s magi. These public events are treated specially because they were witnessed by regular people and demonstrate that they were of divine origin. The super mundane that didn’t have to be practiced in private to witness the results (magic was accepted as real, it was the fact these events were public that made them notable).

I used a lot of Biblical examples because there’s little separation between the mystical practices of Sumerian inspired Babylonians, the Jews, Egyptians, Greeks and Islam. The deities, beings, spirits and creatures vary, but the actual practices involved are not very different. All demand privacy and secrecy. Only certain individuals could engage in these practices and the public are prohibited from even knowing about what goes on.

The implication being that the involvement of, and even the presence of, the uninitiated and unclean will prevent the super mundane/paranormal from being actualized. It cannot manifest except in the presence of the pure, the believer. The exceptions to this invariably involve the direct intervention of a deity (Achilles, Hercules, Moses, Gilgamesh, etc… all had direct involvement with deities).