Suggest a search on the topic in the archives ..
(a) certification (AFM) Vmcg ignores wind (older UK certificated aircraft use a 7kt crosswind basis which will increase the value compared to the US value)
(b) crosswind considerations are pragmatic and should be considered by pilots, especially in the case of low weight, ferry type flights. The certification Vmcg will increase by (typically something in the vicinity of) 0.5kt/kt (twins), 1.0kt/kt (four engines) so, in the case of a takeoff at low V1 in a strongish crosswind, the "actual real world" Vmcg easily can exceed the book figure .. good case for delaying the takeoff until one gets better conditions or use a higher speed schedule.
(c) better to keep the "critical engine" term (for Vmcg) to apply to the certification case and use some different or qualified term to distinguish the real world crosswind consideration ..
(d) for Vmca (once the aircraft is away from the ground and stabilised), steady wind should have no effect ..