Feeneyites hate official docuмents of the Church approved by a valid Pope. Yuck.
Except that
Supreme Haec is not official (aka "authentic"), nor is there any evidence except within the letter itself that it was approved by Pius XII. SH is very likely a complete fraud, a hoax perpetrated by Cushing and his allies. Cushing waited for a couple of years after it was allegedly written to publish it, until JUST after the Cardinal who allegedly signed it passed away. So it's highly likely that this docuмent was, at the very least, heavily edited, and most likely fabricated out of thin air. That would explain why it never made it into the AAS.