What is this technique for matching cabinet veneers called?
Those veneers are without doubt book-matched, but I would say in a very specific method, "Architectural end matching" (End or Butt Matching):


Matching between leaves


P.S. That is some top quality veneering, the attention to detail is almost pure art (the cabinet maker that did that work is an artisan).

This morning on twitter, I asked a few woodworking experts (at least I consider them experts) to take a look at your question:


My initial tweet
@WoodWhisperer initial reply
@MBWPodcast reply
@WoodWhisperer follow on reply
@RenaissanceWW reply