I tested this method. I clearly understand what you did with mklink - you have faster access to the preset files and thats’s all.
Anyway Cubase stores the original path in Project and it is the same - “C:\Users\UserName\AppData\Roaming\Steinberg\Track Presets”.
So if you copy your project and all presets it use to second computer, of course they all are accessible (this post isn’t about access), but they aren’t connected to the project and you cannot reload track preset unless you load it from presumably the same place on second computer. Yes, you can load the same preset, but cannot reload it as it is possible on the computer where you saved that preset.
Please, @skijumptoes, check this! Try this - load Kontakt, load any library in it, store as Track Preset, then copy project and that track preset to second computer (preset in presets folder), load project on it, remove library from Kontakt and then press reload button - that small round arrow
Is your track reloaded? Mine not, because second computer doesn’t have the same original folder structure even mapped, substituted, mklinked drives and folder are identical.
Nice! I wish I had done that. Maybe I will when I upgrade to C12
I solve the original specified problem on this thread by exporting Track Presets. and I do it folders at a time.
It doesn’t matter how to change/fix/implement, but the projects aren’t 100% portable. Trackpresets are one, self created IRs for Reverence is another example, the path to the IRs are stored absolute in the preset.
And when we’re talking about macOS and Windows … you can multiply this “problem” two times.
Within MediaBay we can associate a folder, here a DropBox folder, and move or copy all needed presets to this folder via MediaBay. I can load a preset on the other machine, macOS or Windows doesn’t matter. Nice. But … modify a preset and save this, you have to type in the name again and copy/move it again in MediaBay to the DropBox folder. On the second machine the reload doesn’t work 
Maybe this differs from @ArthurNeeman idea, but for me a folder (the one and only!) configured in Cubase where all presets, own samples,IRs, whatever are located. Not 100% perfect but it works in most cases in another DAW build 7km away from Steinberg HQ…
But should be! Your baggage, your timeline should be independent so if one day you lose your computer, you get to another (or buy new) and continue your job even they are old projects.
We are in 21st century, not 80ies and floppies.
One of the reason why Steinberg will get rid of USB eLicenser is that many composers are working on more than one computer even many of them already bought second license or using hacked version on second computer.
So if I pointed to this unfinished feature now, it means that it should be fixed at the time when almost all Cubase users will reconfigure their studios after Cubase 12 released with new activation system.
I use Dorico 4 and new system works well. Some other people posted that they have huge problems, but as always - not every computer is ready to be a studio.
So simple!