I have to admit that the things that got worse are fixed in the meantime. So there are only the flaws and bugs left that were already there in Dorico 3.5 – and that are a lot 
The most annoying thing is: If you have built a chord symbol, let’s say Bm7/b5 (and yes, the academy were I teach wants that slash), you can’t copy that to another root letter like to Am7/b5 – you have to built the whole thing from scratch, choosing fonts, sizes, distances etc.
My wish list for the preferences would start like that:
– Change the distance between the A and the 7 in A7
– Choose if the 7 should be considered just one of the elements on the higher level (like b9 or #11) or been treated separately (as Dorico always does).
– Choose slash a a divider, not only space or comma
– Choose different fonts for root letter and additions
My wish list for the custom chord symbol module would start like that:
– Copy elements or complete groups of additions (like m7/b5) from one chord symbol to another, or better: Treat these groups of additions separately from the root letter
– Complete renovation of the module where I build the chord symbols from scratch. It takes 2 minutes to build a quite normal chord symbol – and only if I know all the distance numbers before and need not to try out things.
And there’s much more …
I hope you get my point (sorry, my native language is german). If you are interested in a closer look I could do a screen video and send it to you.
For me chord symbols are crucial – most of the time I do leadsheets or gospel choir arrangements with many different symbols, and the results have to be ready for publishing.
Thanks for your patience
Peter