Changing the working model of the cipher family (after 3p). Three results that no substitution key can change, all using N1-r1/N2-r1. Code and outputs are on the baseline task.
The consonants look unenciphered. Ranking the 21 consonants by frequency, the notes track English with Spearman 0.70. Random relabellings reach that about once in 10,000 (permutation test). A random substitution key would destroy that ranking. Exceptions: H is almost absent (4 of 558 consonants, 0.7%; English 10.3%), TH never occurs, and X is about 10 times the English rate. A, I, O and U together are 5.6% of letters; E is 18%.
The letter order is formulaic, and not English order. Next-letter entropy is 2.68 bits. All 12 English transforms I tried (prose, vowel-dropped, consonant-only, initials, word endings, first-2/3 letters, etc.) score 3.05 or higher, over 60 same-length samples each. 47% of positions sit inside a repeated 5-gram, vs 27% in prose.
The notes share their own "grammar". A letter-pair model trained on note 1 alone (360 letters) predicts note 2 at 3.60 bits per letter. Same-size enciphered-English controls reach only 3.96–4.23 this way. English under its best relabelling scores 3.77 on note 2, and vowel-dropped English 3.59, a tie. Shared units include NCBE (13 times in note 1 / 4 in note 2), WLDNCBE (4/2), RCBRNSE (2/2), PRSE (6/1), RCMSP (1/1) and NMRSE (1/1).
Negative spot check: glyph variants don't look like hidden extra symbols. TFRNE is written with a capital R in N1-L02 and a looped R in N1-L08, and B takes two forms within N1-L02.
Proposed model (tentative): letters mostly in the clear, drawn with English frequencies, arranged in a closed, repetitive notation. Candidates are a personal shorthand for a list, with fixed units (NCBE, WLD, PRSE, SE) acting like code words, or pseudo-writing. The fitted abbreviation rule (drop A/I/O/U/Y and H, keep E, keep first letter) matches single letters well, but only 27% of groups decode as dictionary words (versus 24% at the top 1% of shuffles), and 37.5% with SE stripped (not significant). So it doesn't produce a reading.
How to tell the two candidates apart: a shorthand should map its units to real words consistently across contexts. Pseudo-writing should show little context-dependence apart from the writer's habits. That calls for list-like or pseudo-writing controls. Those need sourced samples, which I don't have. Contributions welcome.

