brake pedal soft. found master cylinder leaking from piston seal. changed master and bleed system. still soft. did the brake booster get damaged.???
It usually requires a factory level scan tool to bleed the ABS after the system has been opened to replace a component.
Tester
It’s easy enough for a diy’er to test that the booster holds vacuum. worth doing, but my guess is the same as above, the "softness " problem will only go away after a proper brake system bleed procedure. And this often requires commanding special modes of the ABS valves requiring a scan tool with those capabilities; i.e. best to hire the pro’s do this step for you.
If your booster wasn’t working right the pedal would get harder not softer. (Though I’ll be happy to hear of failure modes that make it softer - ?)
Did you bench bleed the master before installing?