As far as I can tell the Zillions version agrees with the interpretation you've gone with in the diagram, with ‘promotion as usual’ meaning mandatory promo to NBRQ upon reaching the last rank. Which is the only obvious interpretation of the wording, even though does leave the pawn stranded there.
As far as I can tell the Zillions version agrees with the interpretation you've gone with in the diagram, with ‘promotion as usual’ meaning mandatory promo to
NBRQupon reaching the last rank. Which is the only obvious interpretation of the wording, even though does leave the pawn stranded there.