Yes indeed, I explicitly noted this, for example, in the case of the Serbian Orthodox church, affusion is the designated method where full immersion is impossible. That being said, in all Orthodox and Assyrian churches, threefold action is required, and in all of these churches, full immersion is strongly preferred.
I would be very interested to know exactly which church you saw this being done at, by the way, since there are a great many eastern churches, especially if one counts the unfortunate presence of Eastern Rite Catholic churches that resulted from schisms which were, in several cases, exploited by the Jesuits and other groups, and the equally unfortunate presence of Protestant and Restorationist churches which sought to spread into the Christian East on the false assumption that the Orthodox and Assyrian churches are somehow defective, idolatrous or superstitious, which is an attitude I have always found both patronizing and uncharitable.
Note that I am not specifically criticizing our shared congregationalist heritage for this, although I would note with regret that the precursors of both the UCC that you are so fond of, which I was once rather heavily invested in, and the CCCC of which I am so fond, that is to say, the Congregationalists, were among those churches to establish a missionary presence in the Christian East, chiefly in India, although they were much less interested in converting Eastern Christians than some other denominations, for example, the Anglicans, Presbyterians and especially the Adventists (conversely, there were many Anglicans who wanted to unite with the Eastern Orthodox).