Thank you for playing and everything you wrote <3
I'll write out the thought process over what you were wondering about:
The differing audio levels for the static is indeed (mosly) intentional. The Light's more subtle volume is as such due to being a part of Remi - barely noticeable as being 'off' to them. His is extremely loud, Remi's fear drowning out everything else. (Bel's is a little bit too loud though, unintentionally).
And the absence of static for the part where they can't tell if the friends are real is because the friends are actually speaking, static being a representation for what it feels like to me when I 'hear' fake speech like this. Remi can't tell, but the absence is meant to hint to the player that it's different than before even before it's confirmed.