I'm also in MA and used to have inkberry (at a former home) with those exact problems. I even considered boxwood first, but it has its own set of issues and is more expensive. I didn't solve the problem--I moved to a new house instead!--so take this with a grain of salt. Yours don't look too bad to me. I think the yellow leaves are just part of the ordinary leaf-drop cycle and not a disease. The black spots are likely a common fungus. As far as the fungus goes, I would personally just clean up fallen leaves and wait to see if it gets worse, because I don't like to bother with fungicides or chemicals. Make sure they're getting enough water, preferably at the base rather than on the leaves, which can make the fungus worse. As for the bare insides, If you google "inkberry leggy" you'll find a lot of pruning advice. I'd suggest trying the pruning suggestions--not now, but maybe in March just before they start to grow in spring--and see if that helps. Next year they'll either look a little better, and you'll be happy, or a little worse, and you can pull them out and start with something new.

This most recent pic is pretty cool for a couple reasons, among them: The larger plant in the middle (and the one to the right in the foreground) is an example of a plant that I repotted in the brief pause after it had fully opened but before it started growing its first fascicle. The smaller plants (mostly out of focus) show individuals left to grow their first fascicles before repotting. Notice how much bigger the other 2 are at the same age!

it always helps to find the full proper name ... and in my version.. i added the word PRICE ... rather than call's TO BUY ... i got the full proper name off calls page ... https://duckduckgo.com/?q=Ginkgo+biloba+%27Golden+Colonnade%C2%AE%27+(JFS-UGA2)+price&t=ffcm&ia=web if you are looking for a narrow version.... Ginkgo biloba ‘Obelisk’ ... might be an alternative .. if thats any easier to find .... in my experience... there are usually many conifers with the same traits.. so if a very specific name fails ... odds are.. you can find others that are basically the same ... why are you focused on this one specifically?? also note ... now is the time to go to your best local nursery.. and see if they can find it ..... and order it in for spring delivery ... since they can order wholesale.. they may have more options than your might.. retail .... ken https://duckduckgo.com/?q=Ginkgo+biloba+%27Golden+Colonnade%C2%AE%27+(JFS-UGA2)+price&t=ffcm&ia=web

Have you contacted the designer? She has a link for you to ask questions.