"How thorough is the cataloguing of Japanese sets? Is it at a similar level as what is seen here?"
No. Gary Engel does a heroic job cataloguing Japanese sets, but American catalogues are far more complete. The basic problem (besides a generally less well-developed hobby) is that a huge number of vintage Japanese sets were made, each of which was produced in (usually) very small quantities. Sean's collection is much larger than mine is, and I have a number of cards that are from otherwise-unknown sets. Finding cards from new sets happens with some regularity (Sean in particular seems to have a knack for it).
But there are a few reasons that this is a particularly exciting find. First, it's pre-war. Very few pre-war Japanese cards have survived. (I don't have any.) So finding _any_ pre-war Japanese card is pretty exciting. Second, it's very different than any known set. Like I said, new sets get discovered fairly regularly, but most of them are minor variations on one another. As far as I know, this one isn't. And finally, it's an American hall of famer. These cards were produced for kids in Japan, and kids' interests was naturally in the local players, so relatively few cards of Americans were produced. (Basically, like this one, only related to the tours of American players in Japan.) And, of course, it's Frisch. So Sean really hit the perfecto on new finds here.
As for who is on the card: it does look like Tom Oliver, but the caption above the Japanese card displayed says that it's Frisch. (
source) Maybe others are, but I'm not good enough with faces to prefer my judgment over the caption on the card.