Walkthroughs for custom maps.

What about Xiedu? Or is it simply that it's logistically impossible to go faster?

There's a walkthrough with pictures and descriptions for Xiedu. It needs to be checked. There's also this interesting starting save from a Chinese forum. This save is from an older version of Xiedu, and it seems that the randomness corresponds to what's shown in the 79-day speedrun, such as the same item dropping from a chest at 80.136.0.