Just some more NieR Dark Apocalypse stuff I noticed that also applies to Puppet's Bunker (so it may have been mentioned back in 5.3 lore thread).

The angelic script is exactly the same as the Black Scrawl text in NieR Replicant... and 2010 NieR, though the angelic script used for T was what looked like a T and not a U. From the wiki:
The four Angelic Script characters that compose the Black Scrawl are Aleph, Cheth, Gimel and Thes, or A, C, G, and T. These characters likely represent the DNA nucleobases of Adenine, Cytosine, Guanine, and Thymine, indicating that the Black Scrawl represents the breakdown of a Replicant's DNA.
Honestly beginning to think Red Girl is/was Sleeping Beauty from NieR Replicant/Gestalt at this point.