It seems generally historians today are quite sceptical of his method, and of "macrohistories" or historical "metanarratives" in general. This is discussed in more depth by u/Bodark43 in this thread and by u/AncientHistory and u/depanneur (thanks also to u/scarlet_sage for having linked this before) here.

I should also "ping" u/AidenMetallist who asked another question about Spengler a few months ago but never got an answer