I mixed haddoni with 2 LTA's in the same system, but different tanks. All was fine. Moved the LTA's into the same tank with the haddoni, with just LR separating them. The LTA's began to shrink, and not appear healthy. Gave the LTA's away.
I mixed crispa with haddoni for a long time, and everything seemed fine. Then the crispa started moving. It ended up on top of the LR, right above the haddoni. Then I came home to find the crispa detached and upside down on top of the haddoni. The crispa was dead in a day or two.
I mixed haddoni and magnifica without noticeable issue.
I mixed haddoni with malu and the haddoni began to shrink and appear unhealthy. I gave away the malu and the haddoni returned to normal within days.
I now have a haddoni and gigantea in the same tank. The gigantea has lost mass in the few months I've had it. This was expected, as the anemone was bleached when I got it. It's color and feeding response has greatly improved, so I'm hopeful that it will begin putting on mass soon.
IMHO, chemical warfare does take place between host anemones. It takes place between many animals we keep. Like soft and hard corals. The amount of damage that occurs depends on many factors. Species involved, total water volume, flow direction, filtration, frequency of water changes, and I'm sure many others. With my malu, no matter how much water I changed, or carbon I ran, I couldn't solve the problems I was having. With the magnifica, my normal maintenance seemed to keep things under control.