Vmgc and Crosswind...
Yes, you're right. I've seen Boeing charts on the 737-200 for this. My memory is poor (as with the rest of me :> : :>), but I'm thinking the increase in Vmcg is significant. Loss of the downwind engine is a problem with high crosswinds in terms of Vmcg. An increase of as much as 10 to 15 kts is possible.
Regarding certification, etc., I can't offer any information. There are guys here in PPrune who are very knowledgeable in this area, though.
Good question!!!!!
Tom