Clearly, something is seriously wrong on your Macs. I have Catalina installed on 2018 Mini and have no issues of any kind with fonts, InDesign, Quark XPress or any of the usual array of apps used in prepress.
I wouldn't pay a nickel for Suitcase Fusion. Extensis has ruined that app. It's incredibly slow now, and actually unstable if you give it too many fonts to handle. And it sure isn't worth $84 a year as a subscription app. We're talking about a font manager here, not Photoshop.
Fonts can't just "stop working". Either the OS upgrade is damaged, or, as often happens (we see it a lot on these forums), fonts go wacky because underlying Font Book databases and caches get damaged during the upgrade process. You should also never have more than one font manager on your Mac at a time. Just launching Font Book causes it to create hidden system files and .plist files in the user account. These, in part, keep track of what fonts are active. Then, even if you aren't using Font Book, it will fight to keep any fonts open or disabled it thinks should be no matter what you're doing with another font manager.
Do these steps in the order listed to reset Font Book.
1) Quit Font Book. Open the Preferences folder in your user account and put the following two files in the trash.
com.apple.FontBook.plist
com.apple.FontRegistry.user.plist
The file com.apple.FontBook.plist keeps track of Font Book's general preferences and activated fonts, whether as a standard or library collection. com.apple.FontRegistry.user.plist keeps track of deactivated fonts. Both may not be present. Delete what's there.
2) Open Terminal and enter this command:
sudo atsutil databases -remove
Enter your administrator password when prompted. This removes all font cache files maintained by macOS.
3) Restart your Mac and immediately hold down the Shift key to boot into Safe Mode. Keep holding the Shift key until macOS asks you to log in to your user account (you will get this screen on a Safe Mode boot even if your Mac is set to automatically log in). Let the Mac finish booting to the desktop and then restart normally. This will clear the remainder of Font Book's database and the cache files for the user account you logged into in Safe Mode.
After this, DO NOT launch Font Book, or you'll just have to do these steps all over again. Test InDesign to see if it is now behaving properly. If not, you have bigger issues.
