Hi!
I've spent some time looking in to this and one of the more clear resources I came across was A Different Christianity by Robin Amis. It tries to uncover, document and trace the inner tradition that went underground at the time Jhanananda described.
One discouraging note in the book is that it clearly states that the inner contemplative tradition as taught at Mount Athos, for instance, is not fully documented anywhere. At that point I put down my research and sent out a grateful thought to Jhananandas work.
Regarding the actual practices, I believe, for instance, that the external practice of the Jesus prayer is a vehicle to the Jhanas as it is said that the goal is to have it "sink into the heart", and then the "heart keeps praying even during sleep".
They also call the highest form of prayer Theoria, which they describe as "looking at, or seeing, or gazing at God". That to me sounds like Jhana. Supposedly one of the effects of this practice is Apatheia, dispassion, which could perhaps maps to what we would call Equanimity.
They also state that the goal of life is Deification - to become so saturated with the energies of God - that one gradually becomes like God - or one becomes God:ified. Both the non-duality of Deificaiton and the saturation concept maps quite will to the teachings of the GWV.
One other indication is the emphasis of needing a guide, a spritual father. That concept I guess all of us who are here could relate to, as without Jhanananda to guide at least me, both passively and actively, I would not have had the confidence to keep walking.
All this being said though, to get access to any form of living tradition one has to wade through enormous amounts of religion, most of which seems dead or corrupt to me.
All of this takes place, of course, in the Eastern church, perhaps with some leakage over to the Greek and Russian orthodox. The great schism between the two halfs of both Rome and the Church was cemented by dispute on whether you could and should know God with the intellect or experientally, ie mystically. The West as we all know and feel went astray and turned God into a legal system. I'm sure other forms of persecution happened in the East eventually.
But the book by Amis is a good introduction to a lot of this. It frequently mentions Boris Mouravieffs Gnosis as well, which seems to try to unite Gurjieffs system with the Orthodox Church and Yoga or something like that.
Lots of the Desert Fathers are interesting, but none are as clear as St John of the Cross or Theresa of Avila that Jhanananda constantly refers to, from the perspective of Jhana practice.
I guess the simple and short answer to the original question is; I believe they call it Theoria - "looking at..."
EDIT: I misunderstood the original question to be about what the called it rather than how they did it. Perhaps Theoria could be a helpful term to try to find info about. But as stated above, I think they themselves don't think it's written down somewhere.
EDIT2: One cool introduction to the Desert Fathers from the folk here coming from a Buddhistic context, could be to read St Mark the Ascetic's On The Spiritual Law - where he basically explains Karma or perhaps even the Dammha (hmm not sure I use that term correctly), that I don't think a lot of Christians are aware are a part of their tradition. It takes as it's stepping stone what St Paul says, that the Law is Spiritual. Anyway, tangential to the topic. But could be a fun read. It has waken me up a couple of times.