Do you have an explanation why the Gemara says (42b) that Schechar haMadi is "Rami" bei sa'arei, whereas chometz haAdomi is "Shadu" bei sa'arei? I thought that Rami might relate to brewing as in "ki ramu sa'arei ba'asinta" when you start to say shehasimcha bim'ono, while shadu is simply adding an ingredient?
All dictionaries translate Rami and Shadi as synonyms- basically to throw, thrust, expel or even to place. Rami is used as an idiom for brewing as you brought from Kesuvos 8a. Also see Bava Metzia 42b and Rami Shichra in Pesachim 113a.
There is also a different Girsa: d'Sharu (soaking) Bei Shichra (Dikdukei Sofrim).
All the best,