Hi Coptic Soldier,
Hmmm to my knowledge the famous one-nature formula of St. Cyrill is often times attributed to Apollinaris. The evidence of it I have not seen either, just the claims. But even if it were true,.. So what?
Homoousion was in use by the gnostics way before Nicea, and it was even conciliarly condemned in 268 because it was again used in a heretical way by Paul of Samosata. Yet the homoousion now stands as a pillar of Orthodoxy. Even IF Apollinaris used it, or maybe even coined it,.. That in itself does not make it unOrthodox. In fact, from what I have read of him his only heresy is that he denied a "soul" in Jesus, he did NOT teach that the flesh of Jesus was "divine" in the way it is often claimed. He DID teach a communicatio idiomatum whereby the Body of our Lord allowed the Divinity to share in fleshly reality and vice versa.
I consider the "One Nature" phrase a strongly Orthodox position,.. Eventho I would allow for a "Two Nature" phrase as developed in the Eastern Orthodox Church at and especially after Chalcedon. There is nothing unOrthodox in Chalcedonian christology, eventho Leo's Tome does have some pretty clear unOrthodox leanings.
About Orthodoxinfo website,.. It is a ROCOR affiliated site (to the best of my knowledge) which is not a canonical Orthodox Church, but a schismatic offshoot of the Patriarchate of Moscow. Their schism is, however, not complete because they are in communion with autocephalous Orthodox Patriarchates who in their turn are in full communion with the Patriarchate of Moscow and Constantinople. The info on Orthodoxinfo is therefore NOT by any means representative of Eastern Orthodoxy, but rather it is representative of a schismatic offshoot of Eastern Orthodoxy (tho they will strongly and passionately disagree with me here). Be that as it may, you will be much better off searching the goarch website (Greek Orthodox Archdiocese of America) which is a fully canonical Church under the Patriarchate of Constantinople.
(yup Patriarchate of Moscow! hehe)