Our parish and many others in North America use a Missal and Hymnal from Oregon Catholic Press. Inside the front cover is an article about “Who May Receive Communion.” It lists Orthodox Christians and members of the Polish National Catholic Church and the Church of Antioch as being allowed to receive in the Catholic Church. From this I assume that their sacraments are valid.
Before Benediction last night, I checked our parish’s OCP hymnal. It specifies the Orthodox, the PNCC, and the Assyrian Church of the East. It says words to the effect that members of those churches may be admitted to communion, but urges them to respect the discipline of their respective churches regarding this. It refers to canon 844, sections 3 and 4, which I quote here from the Vatican website:
§3. Catholic ministers administer the sacraments of penance, Eucharist, and anointing of the sick licitly to members of Eastern Churches which do not have full communion with the Catholic Church if they seek such on their own accord and are properly disposed. This is also valid for members of other Churches which in the judgment of the Apostolic See are in the same condition in regard to the sacraments as these Eastern Churches.
§4. If the danger of death is present or if, in the judgment of the diocesan bishop or conference of bishops, some other grave necessity urges it, Catholic ministers administer these same sacraments licitly also to other Christians not having full communion with the Catholic Church, who cannot approach a minister of their own community and who seek such on their own accord, provided that they manifest Catholic faith in respect to these sacraments and are properly disposed.
So you see, the neither the PNCC not the ACOE is mentioned explicitly here at all, only the “Eastern Churches” or what we have referred to as the Orthodox in this thread.
Section 3 mentions “other churches which… are in the same condition.” This would cover the ACOE or that part of the ACOE that recently came into full communion.
It should be clear that these sections of the law only specify who may be admitted to communion, penance, and anointing, and only obliquely refer to the status (“validity” if you insist) of the sacraments in those other churches, with the words “provided that they manifest Catholic faith in respect to these sacraments.”
I think the reticence of the law to name any other churches or communion of churches speaks volumes. For the RCC to acknowledge the sacraments - leaving aside baptism and marriage - outside communion with Rome and the Eastern Churches, would be to lend authority to those other churches.