While the Orthodox do not accept the term ‘transubstantiation’ neither do the Eastern Catholic Churches, they have the same understanding, and even use the term:
“In the celebration of we believe the Lord Jesus Christ to be present. He is not present typically, nor figuratively, nor by superabundant grace, as in the other Mysteries, nor by a bare presence, as some of the Fathers have said concerning Baptism, or by impanation, so that the Divinity of the Word is united to the set forth bread of the Eucharist hypostatically, as the followers of Luther most ignorantly and wretchedly suppose. But [he is present] truly and really, so that after the consecration of the bread and of the wine, the bread is transmuted,
transubstantiated, converted and transformed into the true Body Itself of the Lord, Which was born in Bethlehem of the ever-Virgin, was baptized in the Jordan, suffered, was buried, rose again, was received up, sits at the right hand of the God and Father, and is to come again in the clouds of Heaven; and the wine is converted and
transubstantiated into the true Blood Itself of the Lord, Which as He hung upon the Cross, was poured out for the life of the world.” - Eastern Orthodox Synod of Jerusalem of 1672 more info here:
cresourcei.org/creeddositheus.html
In addition the Eastern Churches (Catholic, Orthodox, and some Oriental) have maintained Apostolic Succession, thus they have Valid, though illicit, Clergy.
Also while the Lutheran Church claims the ‘real presence’ they believe the erroneous belief of ‘the sacramental union’ which while not ‘consubstantiation’, still denies the fullness of the transubstantiation of the Bread and Wine into the True Body and Blood of Jesus, thus the intent is flawed which means there is no Consencration.
Even if the intent was not flawed, the Lutheran Church has not maintained Apostolic Succession (Luther was a Priest not a Bishop, therefore he had no power to Ordain) so the Clergy would not have the Sacrament of Holy Orders necessary for a valid Consencration.
Laus Deo