Map from Mystia Izakaya is very nice indeed, yet there aren't every single location. Implementing those might become an issue (not a big one though). Mystia Izakaya itself seems like an interesting random event to occur during travels at night. For that there must be a reason to adventure in night aside from battling Youkai in their prime time. This Izakaya might have a small chance to be encountered, will provide good food for the cost similar to the fan-game. This food and booze will provide some cool buffs to the players.
I think there is good bunch of things you can add from the fan sphere of Touhou. There are heaps of content out there. Ranging from food preferences of named characters to certain apples looking suspiciously bad!!