the LH vs RH i deal makes sense, my Gottschalk piece I just started learning for the Spring term had a m. and I was like what they heck (i am used to md ms norally)!? finally figured out it (main gauche (seen as MG in French piano music) indicates that a section should be played with the left hand, and can be seen on the treble or bass staff vs MD main droite...)
if there's confusion on actually following the designation, let the music be they guide, learn it both ways and use the easier technical approach that allows proper interpretation and technical execution of the gesture in the music with the least physical difficulty. I mean after all we tend to make technical decisions for musical reasons right?