The Decree of the Synod of Constantinople (1755) does not reject economic canons on the question of baptism. It is therefore not a “reversal” of Constantinople (1484) or Jerusalem (1672). According to Father George Dragas:
It is clear from this Ηοros [decree] that the main objection to Roman Catholic Baptism was primarily the manner in which it was celebrated. There are clear references by nuance here to the absence of triple immersion and to the Western innovation of celebrating baptism by aspersion, which was sanctioned by the Council of Trent. (Source)
In other words, the council decreed to reject Western baptisms because they all have improper form. Because Iasi (1643) and Jerusalem (1672) presumed upon proper form, one is compelled to conclude that Constantinople (1755) is the logical conclusion of the councils that preceded it. If an economic reception of baptism is predicated upon proper form, and form can only be altered due to necessity making proper form impossible, it is expected at some point the Church would explicitly forbid the sort of baptisms she was never allowing for.
As follows is a portion of the 1755’s decree, with the relevant portions embolden:
When heretics come over tο us, are their baptisms acceptable, given that these are administered contrary to the tradition of the holy Apostles and divine Fathers, and contrary to the custom and ordinance of the Catholic and Apostolic Church? We, who by divine mercy were raised in the Orthodox Church and who adhere to the canons of the sacred Apostles and divine Fathers, recognize only one Church, our holy catholic and apostolic Church. It is her sacraments, and consequently her Βαptism, that we accept. Οn the other hand, we abhor, by common resolve, all rites not administered as the Holy Spirit commanded the sacred Apostles, and as the Church of Christ performs to this day. For they are the inventions of deprαved men, and we regard them as strange αnd foreign το the whole Apostolic tradition. Therefore, we receive those who come over to us from them as unholy and un-baptized. In this we follow our Lord Jesus Christ who commanded his οwn disciples tο baptize, “in the Name of the Father and the Son and the Holy Spirit” (Matthew 28:19); we follow the sacred and divine Apostles who order us to baptize aspirants with three immersions and emersions, and in each immersion to say one name of the Holy Trinity (Apostolic Canon 50); we follow the sacred Dionysius, peer of the Apostles, who tells us “to dip the aspirant, stripped of every garment, three times in α fοnt containing sanctified water and oil, having loudly proclaimed the threefold hypostasis of the divine Blessedness, and straight α way to seal the newly baptized with the most divinely potent chrism, and thereafter to make him α participant in the super-sacramental eucharist (Οn Ecclesiastical Hierarchies, ΙΙ: 7, PG 3:396); and we follow the Second (canon 7) and Penthekte (Canon 95) holy Ecumenical Councils, which order us to receive as unbaptized those aspirants to Οrthοdoxy who were not baptized with three immersions and emersions [cf. Dositheus, Dodekavivlos, 525], αnd in eαch immersion did not loudly invoke one of the divine hypostasis, [i.e. wrong wording in the baptismal formula, such as merely baptizing in the name of Jesus Christ] but were baptized in some other fashion.
We too, therefore, adhere to tlιese divine and sacred decrees, and we reject and abhor baptisms belonging to heretics. For they disagree with and are αlient to the divine Apostolic dictate. They are useless waters, as St. Ambrose αnd St. Athanasius the Great said. They give nο sanctifιcation to such as receive them, nor avail at all to the washing away of sins. We receive those who come over tο the Orthodox faith, who were baptized without being baptized, as being unbaptized, and without danger we baptize them in accordance with the Apostolic and synodical Canons, upon which Christ’s holy and apostolic and catholic Church, the common Mother of us all, fιrmly relies.
According to Dragas, despite the decree obviously referring specifically to form, those following akrevia would in rare instances baptize Uniates (and I presume Oriental Orthodox). I conclude that Constantinople (1755) is not specifically a council asserting akrevia. It is in fact a council following the canonical logic of economia and applying the discipline of forbidding baptisms due to defects in form.
Orthodox Christian Theology 
Why St. John Maximovitch did not followed this tipycal iconomy?
Russians tended to follow Moscow 1666-7. Implicitly, they follow St Peter Mogila’s interpretation of intent which allows for all affusions to be legitimate, not Aquinas or Dositheus.
Ok this could be getting to the heart of the current division between parties, which I pray will be resolved with some grace soon.
Correct me if I’m wrong, but it is akrevia and not economia to receive heretics who have been baptised with correct form without baptism, because such a baptism would indeed be an offence to God. This is according to Constantinople and Jerusalem. They distinguish those who have not been baptised properly and the akrevia is to baptise these. Economia remains more or less as outlined in the Didache, correct?
And in their context, Roman Catholic baptisms for centuries would have been correct and the akrevia would be to receive by either chrism and/or profession of faith – I’m not sure if chrism is necessary or if RC confirmation is considered correct.
But now you’re pointing out that this later council, without contradicting those prior, brings this up to date to account for the changes Roman Catholicism made that alters their baptisms in a manner that (again correct me if I misunderstand) essentially makes an economia – sprinkling as if enough water for full emersion were not available – the norm. Now it is on this basis that this council decreed it akrevia to receive these by baptism?
So then, assuming I have not mispoke, what of those who have been received according to the first councils in modern times when baptism was more appropriate? Can we assume that their life in the Church is full by grace?
As always, thanks for the stellar work you do Craig, and God bless.
In short, economia is fine as long as there is proper form. 1755 decrees there is improper form and so it is valid to hold heretics to the full measure of the Apostolic Canons.