The yellowishness might have been due to the type of gelatin used, not just the mordant present. Tranfer times are typically in the range of
several minutes per dye, not seconds. There are some ongoing hypotheses about gelatin too, even among those of us using fixed-out paper, regarding what is best. Jillions of variables, really. The one key variable I can't pin down yet is simply enough free time to do this kind of printing! But I find it appealing from the tactile standpoint.