Nah. Had a "what if" at first, but then the "plot" point (literally figuratively) about concave nips kind of reaffirmed that there is no fuckery going on with Tepeste's gender. Just your regular "act more like a girl" thing.
Not sure how you came to this conclusion. Nothing to imply juuse/white whistle were stolen. Nothing to imply that she saw Reg specifically, rather than his "sis". Also, the note was on Nishigora, likely so she just doesn't forget important instructions/info (she is brawn, not brain after all)...