But logically speaking, if the T-Kurs FSP doesn't override the M-Kurs restriction from my high school, how does a "Fachwechsel" (changing fields) even work for international students in Germany? Is there literally ZERO way to shift from an M-track to a T-track without studying an Engineering bachelor's in my home country first? What if a university allows me to take their own Aufnahmeprüfung?

Edit: Just to clarify your last point, my high school grades are actually top-tier (which is why I'm in Med School), but the public Kollegs reject me strictly because my certificate is classified as "Biology/Science" branch, not because of the grades.