Learn English – What does language-neutral mean

Collins defines interpenetrate as:

verb

1. to penetrate (something) thoroughly; pervade

2. to penetrate each other or one another mutually

Under Derived Forms is listed:

interˈpenetratively adverb

So uninterpenetratingly means, "not in a thoroughly penetrating or pervasive way."

To stand invisible and uninterpenetratingly is to stand in a way that can not be seen or felt because it has no detectable effect on you.