No. The offset bracket the OP is using is a different story. But a regular 4 to 2 bolt adaptor works just fine with the standard manual brake push rod. I have a stock manual brake rod and a 4 to 2 adapter from DoctorDiff, with one of his master cylinders.
It is possible for the master cylinder to leak internally. If the seals are bad it can create a situation where you never get a hard pedal. Like I mentioned earlier, I had a brand new master cylinder that was bad straight out of the box, no amount of bleeding solved the issue. I replaced it and everything was fine.
Now, whether or not that’s your issue or the OP’s issue is a different story. But it’s possible.