Thanks for your work.
I made some cmyk transfers onto albumen coated mylar a while back with my screen printing sensitised tissue, but at 3.5 min exposure I did not get enough density (close though) and the yellow transfer was very thin, so maybe yellow needs more exposure even than black, I was using the edge of an A3 tissue though so that could be the cause. Also it stains the cyan tissue so much that it looks green. I will be interested to hear how the stuff you have works and if it is strongly yellow staining.
This is now my busy period at work so things have stalled and wont progress for a few months.