Every aspect of the survival logbook - altered text, red writing, the book itself - work together to bring us the Cassidy Code.

[Amazingspore1026]

Page 29 being changed to page 5 | 2 (the letter C) is altered text (while faded text draws an arrow point saying "MY NAME") Pages 32 (changed to page 3 | 9, gives letter A) & 43 (altered to 1 | 5, gives letter S) also have their page number text altered, and page 47, which gives us 7 | 2 (gives the secondletter S), is found via altered text in a survey. (also accompanied by "MY NAME")
9 | 3 (letter I) This is an interesting one because there is no altered text here - the number is given via a drawn panel of a comic that - on the the chalkboard behind Foxy! There is no way that the in-universe creator of the logbook could have been in on Cassidy's name!
Page 85 has 10:11 (letter D) altered to red, generally agreed to be Mike's color and again, altered text.
8:11 is apparently supplied by Mike, even though there is no real reason why he would be participating in Cassidy's code. (Letter Y)
Finally, several of these clues are accompanied by "MY NAME" in normal faded text.
While the result is undeniably 'Cassidy', it brings into question how much of this is an in-universe book, or a book while, with lots of references to the games, simply exist to bring us the name.