Many relate the critical engine concept to local wind conditions.
If this were true, Vx would vary with wind, V(best glide) would vary with wind, V(best range) would vary with wind... and the list continues.
Speaking not as an airliner pilot, but as a teacher of Principles of Flight, it results in the best conceptual understanding if instructor pilots and student pilots stick to textbook and certification definitions. Otherwise, very quickly, there are no simple answers, and little understanding occurs.
"Which engine is critical?" - well sir that depends on the wind.
"All right,
assuming nil wind, which engine is critical?" - well sir that depends on which side of the cambered runway the aircraft is on.
"Fine. In 5kts crosswind from the right and 0.12° slope to the left, at 78KTAS (Vr being 85KTAS), which is the critical engine?" - Oh I wouldn't know sir, that's very complicated mathematics.
If your textbook relates the critical engine concept to local wind conditions, it's fair to talk about it. Otherwise, perhaps not.
Cheers,
O8