Rabeinu Yona is a raya farkert since he could have easly answered his question and didn’t.
So basically your entire point is that we don’t know why the rishonim thought techeles was blue, and really it would make sense to say it is green, so why were they madche to say it is blue. However, you agree that they punkt happened to be right. If so, maybe the makor of the rishonim was a mesora, (just like the tiferes yisrael, and the radzyner write)
Anyways i dont think there is that much to be mosif, however please check out the article on the color in that kuntris.
as far as the raavad agreeing with rambam, it is more mistaber the raavad disagrees since he holds the chulyos are lavan and techeiles together. the rambam who holds all chulyos from techeiles pashtus learns ????? ?? ????? ???? ?”? to mean on the tzitzis (lavan) there is techeiles and the tachlis of the mitzvah is to wrap (therefore it is on the lavan) and to wrap you don’t need more that half a string.
the emek bracha says it very nicely:
????? ??? ????”? ???? ??? ????? ???? ?? ??? ?????”? ?????”? ?????? ???? ???? ??? ????”? ????? ???? ??? ???? ?????? ?? ???? ?? ?? ???? ????? ???? ???? ??? ?????? ????? ?? ????? ???? ???? ???? ???? ?? ????? ????? ????? ?? ?????? ??”? ??? ?? ????”? ??? ???? ???? ????? ???? ???? ????? ??? ????? ????? ?? ???? ???”? ???? ???? ??? ?? ?????? ?? ??? ??? ???? ????? ???? ???? ??? ????? ?? ???? ???? ????? ??”? ????? ?? ??? ??? ????”? ???’ ?’ ?? ??? ??????? ?? ??????? ????? ?????? ????? ??? ?????? ?????? ???? ?????? ???? ???? ???? ?????? ?????? ???? ????? ????? ??? ??????? ???? ???? ?????? ????? ????? ??”? ?????? ????? ???? ???? ????? ?? ?”? ?????? ??? ?? ????? ?’ ?????? ??????? ?????? ??? ??? ??? ???? ????? ????? ?????? ???? ??? ???? ?????? ??? ????”? ??????’ ????? ?? ?? ????”? ???? ??? ??????? ????? ?????? ??”? ?? ???? ??? ?? ???? ??? ??? ???? ???? ????? ????? ???? ??? ??? ????? ????? ??? ????? ?????????? ??? ???? ??? ?? ?? ?? ????? ???? ???’ ??????? ???? ??????? ????? ????? ??? ?????? ??? ???? ????? ??? ?? ????”? ???? ????? ???? ???? ????? ??? ?????? ??? ????? ????? ?? ????? ???? ???? ???? ???? ????”? ?????? ??”? ?”? ??????? ??? ?????? ????? ???? ?? ????? ???? ????? ???? ????? ????? ?? ????? ?????? ??? ????? ??????? ??? ????? ????? ????? ?????? ????? ???? ???? ????? ?? ???? ???? ?????? ??? ??? ?’ ?????? ?????? ??????