The Thaumic Warden Aspects cannot be get into the AE System with import buses. Maybe try iterating over each aspect, I assume you are adding them manually right now?

In order to generate fluid textures for each aspect I iterate over them during the preinit event. If another mod's preinit event fires after mine then I don't see the aspects.
I may end up dropping the procedural textures so that I can iterate the aspects on postinit, and give all essentia gas the same texture.

What it boils down to is trying to work with EC2. Since you can see the essentia fluid in the EC terminals.
But I feel like its more important to support all other TC4 addons.

You could add the other TC4 addons as soft dependencies, so they load before your mod does.

Yeah, that's what I'm doing now, but I would like to be able to support all TC addons.

Maybe it is possible to check for mods that add TC as a soft dep then try to load after them?
Do you really need to register the fluid textures in preInit? So it differs a lot from the block textures?

http://www.minecraftforum.net/forums/mapping-and-modding/mapping-and-modding-tutorials/1571484-forge-1-6-x-mazs-tutorials-custom-sounds-fluids#entry23300693
Here at least in 1.6.4 it was possible to just use getIcon and a custom color modifier for the icon what could be used for the aspects. If you handle the color managment based on a list you can generate that at postinit without problems I think.

As it so turns out, I was confusing the "preInit" event and the "TextureStitchEvent.pre". The TSE.pre event doesn't fire during nor directly after the preInit event. All essentia fluid code has been moved to the postInit event. Should fix all future compatibility issues with essentia/aspects.