Since no one has stated what they mean by "canonical," I cannot pontificate
on whether the Milan Synod does or does not meet a specific definition.
I can say that Milan Synod clergy have served, in rank, without any reordination whatsoever, in the ranks of Metropolitan, Archbishop, Bishop, Priest, and Deacon, in churches of the Ecumenical Patriarchate, Orthodox Church in America (OCA), Moscow Patriarchate, Romanian Patriarchate, Polish Autocephalous Church, and Serbian Patriarchate, when leaving the Milan Synod behind them. I can say that clergy of the Milan Synod have concelebrated the Liturgy with clergy of the Moscow Patriarchate and Romanian Patriarchate.
That is different from the Milan Synod being recognized officially by any of those Local Orthodox Churches. It is not.
Here are the historical details, from a public post I made Feb. 6, 2008, on the Occidentalis group for discussion of the Western Rite in the Orthodox Church:
IN HIERARCHICAL RANK. Metropolitan Gabriel of Lisbon and his vicar Bishops Iakovos and Theodoros were received in rank into the Polish Orthodox Church in 1989. Metropolitan Gabriel, without intermission, simply began serving as a Metropolitan of the Polish Church. When in Europe rumours began to circulate that they had undergone a fresh ordination, Warsaw confirmed, in a document dated Feb. 11, 1991, that no re-ordination had occurred. An official letter from Metropolitan Gabriel of the Polish Autocephalous Orthodox Church, dated Mar 14, 1993, also confirms that no reconsecration of the Bishops occurred—they were received in their episcopal dignities.
Archbishop Lazar of Ottawa (a defrocked former Deacon of the Russian Church Outside Russia who had been rehabilitated by the Free Serbian Church) and Bishop Varlaam of Vancouver Gabriel, both of whom were consecrated to the episcopate by Metropolitan Evloghios of Milan, but later abandoned the Milan Synod in order to join the Kievan Patriarchate, were received as retired Hierarchs by the OCA on May 24, 2002. They are listed on the OCA's official website as Hierarchs together with Theodosius, former Metropolitan, Gregory, former Bishop of Sitka and Alaska, and other retired OCA Hierarchs. Metr. Evloghios consecrated Abp. Lazar on Sept. 28, 1990, Bp. Varlaam on Apr. 1, 1994. (reference:http://www.oca.org/pages/ocaadmin/episcopacy/index.html#retired
Abp. Lazar and Bp. Varlaam concelebrated with Metr. Herman of the OCA on July 23, 2004, during the triennial Assembly of the OCA's Archdiocese of Canada.
IN PRIESTLY RANK. In France, in 1989, Archpriest Gerard de la Garde and Deacon Joseph Fouilleul, two clergy ordained by Metr. Gabriel of Lisbon, were accepted into the Moscow Patriarchate, without reordination, by the Exarch Vladimir (Sobodan), presently Metropolitan of Kiev of the Autonomous Ukrainian Orthodox Church (Moscow Patriarchate).
When Metr. Gabriel and his Bishops were received in rank into the Polish Orthodox Church in 1989, some 30 of their Priests were likewise received, in rank, into the same Polish Orthodox Church.
IN DIACONAL RANK. In Germany, the Exarch of the Serbian Orthodox Church Lavrentije (now Bishop of Sabac-Valjevo), received Deacon Basil Manfred Danfeld, a resident of Berlin, ordained Nov. 28, 1989 by Metropolitan Evloghios of Milan. At Bishop Lavrentije's request, Metr. Evloghios signed an official letter of canonical release on Mar. 5, 1991. Fr. Deacon Basil was received as a Deacon without reordination.
There have also been cases when clergy of the Milan Synod were received into other Orthodox Churches WITH reordination. But the fact is, there would be no theological barrier to the EP's receiving a Milan Synod Bishop in rank. It is not likely given the politics of the situation, however.
When I applied to the Russian Orthodox Church Outside Russia, in late 2004, I was initially told that I would most likely not need to be reordained. In the end, it was decided to receive me and the other nine or so Milan Synod priests who have left the Milan Synod for the Russian Church Abroad, by the process of a cheirothesia.
I have since concelebrated the Sacred Liturgy with clergy of the Antiochian Archdiocese, Serbian Patriarchate, and Ecumenical Patriarchate.
I hope this will be useful information to some.