Thank you for your expert advice. Yes, I see in Monterey the User Fonts under Option > Go > Library > Fonts which contains the plethora of fonts old and new.
I assumed incorrectly that partitions would maintain separation between OS resources. I wanted to use older applications such as Adobe CS3 Suite that are incompatible with the newer MacOS with best performance when residing on my internal SSD, which is why I added High Sierra onto a different partition.
According to your information, this conflict means I should dump High Sierra and relegate all older applications to an older computer with MacOS El Capitan (speaking of "ancient"). That is disappointing, along with the obsolescence of many of my fonts, but since I have other computers I won't be suffering too much if I leave Monterey exclusively to its own resources.
Originally, after had installed Monterey on the fresh SSD, I found out that I could make a new partition (which I don't think I could have done with a regular HD). Will I be able to erase the added partition from the SSD without affecting the other one containing Monterey and the accompanying modern applications? This would be my first step before dealing with the font issue.
Thanks again for your help.