Thanks for checking Rob, and I did modify that setting after seeing your comment. Pepinello, the addition of the ledger lines, as Daniel pointed out, makes your examples a bit more complicated than mine. I guess I wouldn’t necessarily be surprised if they needed a bit of manual tweaking with ledger lines, but my example seemed pretty straightforward so I wasn’t expecting to need to adjust it manually.
Here’s an example without a grace note, single staff, no manual adjustment, 96.0% full:
I might be wrong, but it looks to me like Dorico applies some kerning between the B and the G# in the second bar to achieve better spacing, but doesn’t apply any in the first bar between the B and the G# grace note. There is definitely more horizontal space between the end of the B and the start of the # in the grace note bar than there is in the bar without the grace note. I wonder if that’s a bug, or just a feature that was never implemented due to complications of handling grace notes. In any case, it does throw off the spacing a bit. It would be great if Dorico could apply the same type of spacing here with grace notes that it does with regular notes.