UPDATE: I can answer my own question: https://archive.org/details/RumourAtNightfall1931GrahamGreen... ; I couldn't find it anywhere the last time I tried!
"Stamboul train" has some Esperanto expressions standing in for Hungarian, and "The confidential agent" has a constructed language called Entrenationo, which the Wikipedia article claims is "obviously modelled on Esperanto" but which sounds a look more like Interlingua to me, though there could be other candidates from around that time. It would be nice to know who the Dr Bellows character is based on. (There's almost no resemblance to Dr Zamenhof.)
The essay is long, and he expresses his dissatisfaction at his inability to say what he wanted to in it, before finishing with:
To most people in any case the whole idea of reforming language would seem either dilettantish or crankish. Yet it is worth considering what utter incomprehension exists between human beings — at least between those who are not deeply intimate. At present, as Samuel Butler said, the best art (i.e. the most perfect thought-transference) must be ‘lived’ from one person to another. It need not be so if our language were more adequate. It is curious that when our knowledge, the complication of our lives and therefore (I think it must follow) our minds, develop so fast, language, the chief means of communication, should scarcely stir. For this reason I think that the idea of the deliberate invention of words is at least worth thinking over.
[1] https://www.orwell.ru/library/articles/words/english/e_words
Knowing so many people who love his books gives me a bit of FOMO, especially after giving up on that book. Would you recommend a different one to start with?
They will give you great insight into the sense of unease felt by functionaries in a dying empire who can sense the end, and react in various ways to this (disillusion, cynicism, outrage, despair). He's also big on doomed or failed relationships which never quite seem to end (in particular catholic marriages), and of course the books shed light on the relationship of a lapsed catholic to God, who pops up when you least expect him. As you may be able to tell from that summary, they are not often light reading, though he does spice the stories with little jokes. A sense of doom and unease just comes with his world view I think and you can never escape that in his novels.
Our man in Havana is quite fun without being too heavy, so that might be a good place to start. The Quiet American is also good and concerned with the end of another empire (the French colony in Vietnam), and the sharp end of the US intervention there.
I’ll reply again with the publisher info if I find it.
I do think that to really 'get' Greene's writing, you should have experienced the cognitive dissonance that comes from religion.
I was introduced to his writing by an English teacher who saw that in me. Truly a teacher who influenced my life's trajectory.
I have loved ; The Human Factor, The Captain and the Enemy, The Honorary Consul, Our man in Havana, The Tenth Man ...
Monsignor Quixote I can also recommend. The others I read I have forgotten, except for Brighton Rock which I didn't like.
As a sibling commenter has said, if you have any form of religious background or have seen that world, his books speak with a depth I think it would be difficult to grasp without that.
A few stories that come to mind that might make good examples are "When Greek Meets Greek" and "The Destructors."