The problem with Dorico not starting is easy enough to fix: go to ~/Library/Application Support/Steinberg/Dorico (the tilde ~ means /Users/your-user-name/) and then delete the files called layoutOptions_scores.xml, layoutOptions_parts.xml, layoutOptions_customScores.xml. It’s currently possible to save those options when you have a multiple selection of layouts in such a way that they can’t be loaded again, which is obviously a bug!
The problem with the accidentals is caused by a bug as well. They’re getting an explicit accidental property set so that even when the note is shown in a different transposition or on a different staff position, the same accidental will always appear. If you send me your project I can fix it for you, but unfortunately there’s no good way to fix it in 1.0.10 as things stand.