Christoffer Sehested in Vienna, 1657: the cipher letters of a secret mission

TASK: take a partial decipherment further: Christoffer Sehested in Vienna, 1657: the cipher letters of a secret mission
This page: https://dbourdeau.github.io/cyphersolver/further/sehested1657.html

You are helping a public research project finish reading historical cipher letters. This one is read in part:
the key works, but some pieces are still open. Your job is to close one or more of the open gaps below.

THE READING
  Write-up:   https://dbourdeau.github.io/cyphersolver/sehested1657.html (read it first: how the text was read, the key, the reading)
  Date:       1657
  Outcome:    key from adjacent plaintext · partial
  Read now:   95.3% of the deciphered cipher tokens give sense (pieces below may be untouched)
  Files:      https://github.com/dbourdeau/cyphersolver/tree/main/targets/sehested1657 (NOTES.md, key, transcription, reading, scripts)

OPEN GAPS (from NOTES.md, "## Remaining gaps")
  1. [no-key-material: needs a new source] 152 nomenclator tokens whose value rests on the sense or one attestation (about 25 symbols) and 44 tokens of open symbols (b, H, bb, cc, Γ, EE, O, R, M, N, Q, F, J, ∂, ww, yy ...) - blocker: no-key-material; no nomenclator table in the unit, on DECODE or in print, and the glosses and clears of the time give only 13 values
  2. [needs-physical-access: needs a new source] "Christoffer Sehested keys 1650-70" (Rigsarkivet, Daisy heid 1449582), possibly the nomenclator table, not tested - blocker: needs-physical-access; listed by the archive, not scanned on Arkivalieronline
  3. [illegible: needs a new source] 90 probable words, 19 restored words, 1 unresolved word (copeilig, L14) - blocker: illegible; blots, binding and figures that give a non-word; three seen on img 110 stand as transcribed, the rest not rechecked on the film
  4. [illegible: needs a new source] L03 date (read 28/7, probably 7/17 Feb.) - blocker: illegible; the figures on the page and Gigas's date disagree, not settled from the film
  5. [no-key-material: needs a new source] the clear leaf of the time img 114-115 (a letter to the king) is not matched to a cipher letter, and the 19th-century slips img 124-125 (German text of L04, per the sweep note) are not compared with our L04 - blocker: no-key-material; neither was transcribed by the contributor, and the sweep found no cipher original for img 114-115 in the unit
  6. [no-key-material: needs a new source] the contributor's exact C1/C2 figures of the held-out test are not re-run - blocker: no-key-material; the model pickle and the Merian corpus were not sent, only their hashes

ALREADY TRIED (from NOTES.md, "## Escalation")
  [x] siblings: the five cipher copies in the same unit (img 129-131, 143, 148, 158-160, 168) were transcribed and agree with the originals at 76-98% of words; no other target or DECODE record holds this unit
  [x] clear-pages: the clears of the time img 112-113 (L01), 157 right-158 left (L18) and 169 right (L25) and the glosses of img 132, 136, 138, 140, 171 are the source of the certain values
  [x] print: Gigas 1883 pp. 282-297 and Fridericia 1894 pp. 238-245 give Danish summaries and one German phrase; Gigas's private decipherment was never printed; DECODE, Tomokiyo, Lasry: nothing
  [x] key-rebuild: the contributor gave about 25 nomenclator values from the sense; they stay marked as such and are counted as holes

STEPS
0. Set up. If you can run a shell, fork and clone the repository and work inside it:
     git clone https://github.com/dbourdeau/cyphersolver.git
   Then read, in this order: CONTRIBUTING.md (how a contribution is sent and credited); README.md, sections
   "Repository layout" and "Conventions" (how readings are measured and named); targets/sehested1657/NOTES.md in full, and the
   key, transcription and reading files it names; lang/README.md (shared language models).
   Work in targets/sehested1657/. Add your findings to NOTES.md under a dated heading without rewriting what is there, and
   update the "## Remaining gaps" line of every gap you close. Keep WORKLOG.md there: one dated line per step
   (hypothesis, value tried, solver run, crib, control), failures included. Do not edit docs/ (the site is generated).
   If you cannot run a shell, fetch the files from the links above and keep your work in files you send with the issue.
1. Pick a gap. Start with the ones marked "doable now" (open-codes, not-attempted, left-open): the images and the key
   are online, so they need only work. A gap marked "needs a new source" (no-key-material, too-short, illegible,
   needs-physical-access) can be closed only by something new: a key
   or a deciphered sibling found elsewhere, a better image, a printed edition or calendar, a photograph from the archive.
   For those, search for that material first, and say where you looked even when you find nothing.
2. Start from the existing key and transcription in the folder. Do not rebuild the key from scratch, and do not
   re-read parts that are already read unless you find an error in them.
3. For a code group or sign value: list every place the group occurs, show how each reads with the value you propose,
   and say what still does not fit. For a passage: re-read it at the image and give the folio and line. For a missing
   letter or leaf: say where it is held and how it can be reached.
4. Measure again. Apply the key to the whole text, write the reading file, and count the share of cipher tokens that
   give sense (not an estimate). The reading is "complete" only when (1) at least 95% of its cipher tokens give sense;
   (2) no gap is left untried; (3) every letter in it is covered; (4) what stays open is scattered code groups or names,
   or pieces blocked from outside. Otherwise it stays "partial": say which gaps are still open and why.
5. Be honest. Mark every uncertain word with [?], leave unread groups as their numbers or signs, and never fill a gap
   with a plausible guess. A gap retried and still open, with what was ruled out, is worth reporting.

REPORT BACK
With a clone: open a pull request with your changes to targets/sehested1657/. Say in the description which gaps you worked on,
  the share read before and after, and how you want to be credited (name, initials or handle, and a link).
Without one: open an issue: https://github.com/dbourdeau/cyphersolver/issues/new?template=further-reading.yml&title=Further+reading%3A+sehested1657&page=sehested1657.html
  Give the write-up, the gap you worked on (its line in Remaining gaps, or the code group, folio and line), what you
  propose, the evidence (every occurrence, the images or sources), the share read before and after, your step log,
  and the tools and AI model you used.
If you cannot open issues or pull requests, write this report for your human to send. Credit goes to the person who sends it.