Being an avid TT fan, I thought I'd weigh in with my thoughts on Yan Lo...
I've only played him once, and I've never faced him before, so my experience with him is limited, but from what I've seen and understand (based solely on what I've read), he is the type of Master that does need moderate advanced planning. I don't think the problem (assuming there is one to begin with) is adding more Ancestors though.
To my best recollection, this was the list I used for my 1 50ss game.
Yan Lo
-Wings of Wind
Soul Porter
Toshiro
Izamu
Yin, the Penangalan
Onryo
Onryo
Punk Zombie
In hindsight, Wings of Wind was probably a bad choice. Granted it did help me get Izamu halfway up the board on Turn 1 and into melee, but Yan has a lot of "0 Actions" he already relies on, and adding more 0 actions just becomes counter productive at that point. Also, I probably could've done without the Punk Zombie. A Monk of Low River would've probably been good, since I had no defenses against Poison or Burning conditions, but otherwise the list was substantial.
I didn't use Chiaki, despite also being an Ancestor, mostly because I wasn't sure how her abilities would work. Maybe instead of the Monk, next time I'll substitute the Punk Zombie for her.
In any case, my general strategy started off with board manipulation and responding to my opponent's movement. Fortunately, I had second initiative on Turn 1, and I believe we were equal on activations, so responding wasn't too difficult (He was playing Kaeris). By the end of Turn 1, Yan's Chi was at +2, thanks to Izamu killing someone within range.
My memory of the rest of the game is hazy, but I remember utilizing "Fury of Yomi" at least twice, making Toshiro a Spirit for at least 1 turn, and making a lot of use with his ability to move just about anywhere. It was at this point I realize his strength is in making his crew stronger and better.
My biggest mistake was misusing Yin. Instead of bringing her towards the middle of the board and engaging my oppositions stronger models, I had her going off to take out his minions. I believe the game ended in a draw, so all in all, it wasn't a bad experience.
Now as far as how Yan Lo can be improved... I don't know if he needs improvement, honestly. Having more options for Ascendent upgrades would be nice, but what else can you give him?
Commenting on his summoning abilities, I think they work well for his fluff. They make him unique in his own way, which TO ME, is the draw for playing him. He's not like the summoners from the Resurrectionists, and he doesn't have to be.