I don't know the answer to that exactly - Frieda Harris' copyright should extend to 70 years after her death, which I believe was in 1962, so until 2032.
But William Breeze, current head of the OTO, himself says in the introduction to The Drug and Other Stories (Wordsworth Editions, 2010 (copyright named as OTO), p. XIV):
"Wordsworth excels at affordable editions of public domain literature, but, whilst Crowley's works published before 1923 are public domain in America, in Europe the works authorised in his lifetime are in copyright through 2017, and his posthumous works through 2039."
(emphasis added)
Note that he doesn't limit the pre-1923 public domain Crowley to works, such as the Blue Equinox, which were actually published in the United States.
It would seem that anyone is free to reprint The Equinox, for instance, if they so wish, as long as it published in the US.
But the "notes" in LWB might be a different kettle of fish, if they were edited and published after his death.