Further AI digging suggests this...
"You will need to use different software. NCH Crescendo relies on traditional modern notation, and while you can alter stem directions, it lacks the specialized tools to hide stems completely or output proper square Gregorian chant notation.
For authentic 12th-century chant (using square neumes) or modern stemless chant notation, the following free and specialized software options are highly recommended:
- Gregorio: The gold standard for professional square-note chant engraving. It is a text-based system (similar to LaTeX) that compiles into beautiful, traditional scores.
- MuseScore: A great open-source graphical tool. You can input chant melodies using standard quarter or half notes, remove the barlines and time signatures, and use dedicated plugins or formatting tools (like the Chant extension plugin) to hide note stems and adjust spacing. [[1](https://forum.musicasacra.com/forum/discussion/20749/chant-notation-in-finale/p1), 2, 3]
- Finale: Industry-standard software that allows you to easily change notehead styles to chant shapes and globally set your stem length to 0 for stemless notation."
File a suggestion with NCH.