Dear Christina: thank you so much, your paper is very interesting. Considering inverse koide formula, Markovitch also uses similar term of 3/2. See link below. Check also Carl Brannen's paper on hadron masses: http://brannenworks.com/hadron
Mi guess is a discrete symmetry, comming from S4. I mentioned it in a video some months ago.
Note that Koide formula also applies to quarks. I fact the first example of a Koide triplet in the literature was (d,0,s), but it was done supposing that the mass of up quark is zero. But also (s,c,b) and (c,b,s) fit Koide