Is the consecration of unleavened bread and wine permitted at a "Gregorian Rite" Western Orthodox Mass?
no
Okay, that makes sense because of the azyme controversy. However, I've never understood the Orthodox extreme aversion to the use of unleavened wafers for consecration.
Aversion to judaizing.
The Lamb symbolism is quite profound. Even so, I suspect that the real reason why the Orthodox insist on leavened bread for the western rites is merely historical and political.
No.
The Orthodox insistence on leavened bread as the Eucharist species seems to me to be a way to strongly differentiate Orthodoxy and Roman Catholicism.
Roman used to use leavened bread, and then abadoned it. We're just sticking to the original way of doing things.
If an Orthodox priest consecrated a wafer, would it not the the body, soul, and divinity of Christ? I find it hard to believe that it wouldn't be.
I think it would, but plenty of Orthodox have no difficulty believing otherwise.
if a leavened Lamb is intincted in the Blood of Christ, the prayer "Corpus Dómini nostri Jesu Christi custódiat ánimam tuam in vitam æternam" at the administration of Communion would need to be changed. Would the prayer be modified to read "Corpus et Sanguinis ...", or is another form used?
Not necessarily. particularly if it were it Latin, unless the DL was in Vatican City perhaps.
Why is the Roman pronouncement at the Communion insufficient?
I didn't say it was.
And also, why is saying it in Latin problematic?
No one speaks it. Why is it problematic not saying it in Latin?
Or, is it just not the custom to say the prayer in Latin?
Not that custom, as far as I have noticed.
Again, I can't see the difference between the Latin prayer and "May the Body (and Blood) of our Lord Jesus Christ preserve your soul unto everlasting life".
The communicant understands one and doesn't understand the other.
The English translations of the prayer are usually quite literal. Is the general disuse of Latin related to the way in which the Latin language is very intertwined with Roman Catholic identity?
Has nothing to do with it. The Paschal Gospel, for instance, is read in Latin (among others) at every Eastern Orthodox Church I've been to.