The fact of the matter is, it's a low-profile tournament in every country but Canada. It's not surprising. It says much more about the status and visibility of this tournament than it says about Buffalo as a hockey town.
Look how successful the NCAA Frozen Four was when it was hosted in Buffalo, for a comparison. Now there is a tournament with some name-recognition in the US. And unlike the WJCs, college hockey is not priced at outrageous, NHL+ prices.
Despite all this, something like 30% (100,000 out of 300,000) tickets in this tournament were sold to Americans, which is the highest-number of American attendees ever for this tournament. I think Buffalo hockey fans supported this tourney about as well as could be expected, but obviously nowhere near the level of Canadian hockey fans, for whom this thing exists on a whole nother level.