I doubt that raising Cornish under asil hens will have any impact on their outcome. The asil that were used to make the Cornish were most likely Desi fowl. Came from the same place, looked the same, but weren't game birds. It has to be there to bring out through breeding. Nothing against Cornish, but the ones I've been around have been pretty dopey. There is asil there, but there is also a lot of other junk. Asil are as pure as they are because they have been tested against other asil., through history. There are many traits that go along with asil that are pretty evident to an asil breeder, so it is pretty hard to make substitutions. Most breeds are fairly easy to replicate. That is why hatcheries have such a hard time with asil. It's hard to get something to lay enough eggs to be profitable for selling chicks to the masses with pure asil stock. No doubt the asil has played a big part in a lot of breeds. Some say the "malay" that is supposedly in RIR was really a Kulang asil. The Wyandotte got a laced pattern and tight comb from somewhere. The buckeyes had a game chicken that was half "indian game" in their makeup. Doubtful that a person rasing games at that time would have crossed a Cornish with his bird, given their track record. A lot of the roundhead American game had asil, this is probably what was on the yard of the guy that the lady that made the buckeyes got her game rooster from.
I don't know about anyone else's, but my asil that turn out wheaten start out solid yellow. The "chipmunk" chicks come out as dark.