Monk AI's aren't that bad, they just aren't flexible, so you have to find a build that suits their AI.
Tahlkora: Tahlkora is not a healing monk. 60% of the time when I hear someone talking about their monks failing they ping their monk builds and they have Tahlkora set as heal. I don't care if you think she's cute or just think Dunkoro is really ugly; Tahlkora fails hardcore at healing. Don't use her to heal. In fact, I have "Gift of Health" on my Tahlkora's otherwise active prot skill bar and even though I put it as skill #1, I'm still not sure if she ever even uses it. Tahlkora does not like the Healing Prayers.
Dunkoro: Dunkoro isn't that great. I think he does well with Healer's Boon but really nothing else other than that. Dunkoro will
never use LoD correctly.
Ogden: Ogden will
always use LoD correctly. Despite being an ugly Dwarf, he's a beautiful heal monk. Once you get Ogden, you should take all of your runes off Dunkoro, give them to Ogden, and never use Dunkoro again.
Seriously: Don't give Tahlkora a healer's build.
BONUS POST
Though for quite some time I have been successfully using a standard equation of 2 Hench monks, 2 Hero monks, 2 eles and 2 melee, I recently found
this paragon support build that works pretty much exactly as described on it's PvXwiki site.
For those of you who don't like running 4 monks try out this para or some variation of it, it works nicely.