Would it be possible to generate a summary table of all settings that have been changed from the defaults for a layout?
So many size/margin/spacing decisions interact that it is all too easy to lose track of what subtle changes led to a particular layout success/failure.
Worse, if you make some bad choices, it is often hard to work out how to unwind them!
No, there’s no feature like this at present. But honestly, your best bet is to delete the layout and re-generate it, which will use the default settings.
In a future version of Dorico we do plan to provide precisely this capability, to determine how your current options differ from either another project or the factory default settings, and to allow you to selectively make adjustments. But no such feature exists in Dorico 3.5 today.