Small clue here too, maybe more subtle:
> explained school director, Rosalina Pfirsich, looking up from her storybook
Pfirsich in German means Peach, as in Princess Peach :D
They’ve also got:
> schoolteacher Yoshi Kyouryuu, mid-way through painting spots on eggs
You somehow identified the last possible, most obscure clue. Mario, Luigi, Rosalina, and Yoshi show up before that.
There is also ”project leader Mario Idraulico”
Also "project leader Mario Idraulico" (i.e. "hydraulic" in Italian) or "Safety coordinator Luigi Fratello" ("Brother Luigi").