As you’ve noticed, Dorico is lacking any settings to adjust these. I created a doricolib file that creates a “Chord Symbols Slash Font” font style, and posted a walkthrough in this thread. If you use that style to reduce the size of the slash a bit, I think you’ll get better default kerning. Using Petaluma, once I reduced it, I get this with no manual editing at all:
The G/A chord is obviously not spaced well, but the others aren’t terrible IMO. The slash is now quite small, but if you can live with it, it may save you a ton of time manually editing these.