Well, yes, same as with Aragon in Sardinia, but the Catalan community there is tiny. As for the Greeks, I think the largest community of Greeks would be located in Apulia, which is not granted to Greece, but instead Calabria and Sicily are. Hence the confusion.
The Logic I fail to see here.. well, maybe that they didn't want to restore an Italian state to challenge the Papacy, but even then there were better choices.
Oh yeah, your points are definitely right - but if this map is crazy-stupid enough with its borders, it's no wonder to me they would try for such flimsy historical justifications.