I use Parallels primarily for Storyline 360 access on my Mac (It's a program to create eLearning courses). I do most of my layout work in Keynote (cause it's such a comfortable app to use and I can access all my saved colours) and then export it to Storyline 360 to add interactivity and quizzes. I keep my custom fonts on my Mac up-to-date, but I sometimes forget to add them to the Windows VM. It would be great it Parallels did an installed font sync, so those fonts that I've added to my user library on the Mac were automatically installed on my PC! I'd be so very happy to never see a missing font screen on the VM again.
Parallels doesn't currently sync installed fonts between macOS and Windows automatically. You still have to manually install any new fonts inside the Windows VM to avoid missing-font issues.