I don't know that M. fauxiana (or M. albilanata ssp. oaxacana as it is now classed according to the botanists), has yellow flowers. The only species in the Supertextae that has yellow flowers to my knowledge is M. halbingeri, whose taxonomic status is somewhat uncertain, anyway. M. halbingeri also has a form with purple-red flowers, and M. dixanthocentron has a number of forms, and the flower colours vary from red to almost a pale peach.
So I'm not quite sure where to put this plant, though I am tending towards M. halbingeri.