Romans were not mentioned in Isaiah 42 thus they cannot be relate to preaching to gentiles.
The meaning of the verse Isaiah 42:10-12 clearly say it will be the inhabitants of Arabia that will travel to far end of earth to proclaim His praise. Not Romans that spread Pauline-Christianity as can be seen today. And indeed inhabitants of Arabia have been travelling to spread New Song since 7th century till today spreading the message that is Islam. Muslims proclaim His praise everyday.