Ferkner it seems to me you are mixing up a lot of things. Please try to inform yourselve about fonts at Mac OS 9, so you will understand for example, that you have to "activate" a font either by the OS or by an ATM for example, so that it is available to all other programs via the OS. That means for example that "Quark" always can use what the OS offers. Btw. very few programs have own or additional "font-systems".
Here are some further unsorted hints, regarding to where I see missunderstandings from your side:
ATM light was formerly "ATM". You need any ATM (light or deluxe) for using PostScript fonts. Below the version 4.5.2 ATM does not work with Mac OS 9 (just 8.6 or below). The last version for Mac OS 9 is 4.6.2, for example here:
https://www.macintoshrepository.org/172-adobe-type-manager-4-6-2A font manager is for activating the fonts that you need (on the fly, without rebooting the programs). So usually you have your system fonts active, and several thousands in your manager, but you just activate the few (10 or 20) additional that you need (as you would not like to scroll thru thousands of fonts in every menue of your programs). Suitcase is the better manager, and can do things automatically for you (read the manual).
ATM light is not a manager, but a "PS System" that is providing PS fonts for your Operating System and the displaying of PS fonts. You need ATM light even if you use Suitcase as manager.
If you like to use OTF fonts, you need to use "ATM Deluxe" as font manager. Suitcase cannot handle OTF (sadly)!
ATM deluxe can be found here for exaple:
https://macintoshgarden.org/apps/adobe-type-manager-46-w-adobe-type-reunion-26TrueType as PS Type 1 Fonts are different for Mac OS and Windows. They are differently "packed" and with different informations, so that you have to use Mac or Win fonts! You cannot simply use the one at the other plattform. There are converters in existance that can convert your Type 1 or TrueType Win fonts to Mac and vice versa.
If you cannot use the fonts, I suspect that you try to use Windows fonts at your Mac?
The 29 Mac OS 9 standard fonts are:
https://www.oreilly.com/library/view/mac-os-9/0201700042/0201700042_ch15lev1sec6.htmlNo need to reinstall the entire system
The Systme Folder can handle up to 128 fonts at the same time.