Borges was aware of Joyce and of Flann O'Brien. He reviewed Swim-Two-Birds in 1939. This is the beginning of "postmodernism" in fiction, surely. Borges's own writing would then feed back into metafiction in English. Both Mulligan Stew and If on a Winter Night come out in 1979. This is probably the high point in the story of "postmodern metafiction." By the time Obabakoak comes out, in 1988, these techniques are super familiar. Now they are still interesting, but as representatives of a style of the past, not as a new technique. I guess a very young person might be excited by it still. I am excited too, but in a kind of nostalgic way.
It strikes me that there is not much connection between postmodernism in poetry and in fiction. Someone like Linda Hutcheon can write a whole book on postmodernism, another on parody, and not mention any poets ever. It's true Sorrentino was poet, too, as was Harry Mathews, but these connections are tenuous. People reading John Barth were not interested in poetry, and people reading Frank O'Hara weren't interested in Pynchon, maybe. Borges was poet, but his poetry appeals to a more conservative, less speculative taste than his essays and stories. I've been reading La invencíon de Morel, too, which has a connection to the French nouveau roman. (Last year at Marienbad.). ??
Those novelists Guerard liked were not interesting to me, now or then. I don't remember who they are any more.