@Terhonator: Go Each facial controller has only a few animations related to the lines they speak. So if you need your portrait to animate for a custom voice sound, you need to check the options for that model and use one of them. Open a sound entry for that unit/character and copy the animation name to your new sound entry.
I just found out that you can read the animation names out of the .fxa files by openeing them in notepad + +.
That can be easier than searching sounds for some portraits.
You need to extract the fxa files out of the mpq files, thought...
open the portrait in the previewer, add the fxa file, right click the fxa in the bottom window and add animations.
For those who might read this thread and not know what to do...
To give a sound a lip syncing movement animation... First, find the unit sound file you want to change (example: "Swann_What"). Then go to "Sound Assets^+" to see the sounds (You can play each of the sounds to decipher each sound). Find one that already has an animation. Double click the sound (or right click and click "modify sound"), then go to the animation tab. Copy an animation file name from one that already has one, and then give it to the sound that doesn't.
So an example of this would be "Sounds" -> "Swann_What" -> "Sound Assets^+" -> [Pick a sound file that has an animation and double click it. For my example I'll use "Swann_What00"] -> Animation tab -> Copy "Swann_What00" next to Facial Animation -> [Find the sound file you want to change or add the animation too. Double click it] -> Animation tab -> Paste "Swann_What00" next to Facial Animation. -> Type "Default" next to Facial Group.
And Voila! Your sound now has facial animations for that unit!