Walkthroughs for custom maps.

Check out HeroeSportal, it might help. Besides Marmot, there are only a couple of other people here who have any real skill.
In the CIS community, and specifically on HeroeSportal, I personally found and uploaded "Heroes of Jin Yong." I found it on a Chinese website, in posts from around 2005, where Season himself hangs out. The map never became popular due to its difficulty.
Harry Potter is also missing from the list; it's a Chinese map, but not by Season.
Try the map "Y2K+1." If you can't find it, I'll send it to you from my personal archive of the best maps.

Thanks for Heroes of Jin Yong; it's currently day 232, and the map offers a very interesting challenge. I've defeated all the AI opponents around (Kreg and Dessa are still holding their own), and I'm waiting for an enemy hero from the Necropolis in the lower left corner of the map to make a move. I'll probably need to pack up and move further away from him soon.

I'm also far from being a master player, and I can't speedrun this type of map, but I'm managing to keep up the pace. HoJY seems even easier than Way Home so far. But I see that later on, some overpowered AI opponents will come through the portals, and they're given flight on their way out. We'll see how I can handle them.

By the way, I recently finished Harry Potter as well. It's a tricky map, especially the start, but Aeris Quamarine couldn't evenly distribute the difficulty across all stages of the game, so from a certain point (specifically, after all the heroes rushing to the starting location have been defeated), the game becomes simple and even a bit tedious.

Also, thank you for suggesting Y2K+1; I'll add it to my list of maps to play. But for now, I plan to try Rise of the Sun King after the Season maps, although I doubt I'll even be able to make it through the first few days. :)

Don't you play these kinds of maps yourself?