Well done for finding those various bits to delete. I’m afraid you’ve caught me in a really busy week; I’m sorry you’ve been looking for answers all day.
I think I’d start a new project from one of the SE Chamber templates, then go to the Library Manager, find an appropriate SE Jazz template (they’re installed to that same place you already mentioned in Application Support, but for reference they’re also in Documents\Scores\Scoring Express Dorico).
You’ll then want each of these Engraving Options bits, and the Chord Symbols Kerning Pairs in the left side:
Click on Font Styles in the left side and grab these ones:
Apply and Close.
That should give you a more reliable Scoring Express (hybrid!) starting point, from which to methodically work through the Engraving Options for Chord Symbols, followed by the Kerning Pairs, followed by individual overrides (as detailed further up the thread).