You somehow went to firmware 4.2 then revert back to 4.1, but the baseband can't be downgraded. That's the only logically way you could have gotten the 5.15 baseband.
That correct, OP you have the 4.2.1 baseband.
All you can do is wait and hope the new unlock works on your baseband version also.
And if you want to keep your unlock stop updating your phone every time there's a new firmware out.
When will people finally learn? Its the same thing every time theres a new firmware update.