Transposed chord symbols do not always undo correctly

Issue type

Engraving bug (incorrect score rendering)

Description with steps to reproduce

If a chord symbol is transposed and the spelling happens to be affected by the option Accidentals: Single # and b only, it will not undo correctly.

E.g. in the attached video:

• B# chord symbol is transposed down by a perfect fourth: F double-sharp
• F double-sharp is changed to G natural, according to the Accidentals option
• Undo
  EXPECTED: B#
  ACTUAL: C (natural)

Supporting files, videos and screenshots

https://github.com/user-attachments/assets/a6cec309-9ba9-4ce5-9f20-1433095694b8

In which versions of MuseScore Studio is this issue present?

4.6.5 - latest main

Regression

No.

Operating system

Ubuntu 24.04.4 LTS

Additional context

No response

Checklist

• This report follows the guidelines for reporting bugs and issues
• I have verified that this issue has not been logged before, by searching the issue tracker for similar issues
• I have attached all requested files and information to this report
• I have attempted to identify the root problem as concisely as possible, and have used minimal reproducible examples where possible

Start by reproducing the attached example: transpose a B# chord symbol down by a perfect fourth with “Accidentals: Single # and b only” enabled, then undo the change. Investigate the chord-symbol transposition and undo handling; done means undo restores B# rather than C natural.