I guess nobody listens for this stuff anymore 8(
For visual cues power aura's is going to be the most obvious, though I believe ECB turns red (or whatever) and cuts out when you're countered.
I'd have to poke around in my logs but I've got another mod (Cooldowncount?) that spams the integer cooldowns ON the buttons themselves. So I can just get a visual cue that oops that was shadow (though if you're listening, you shouldn't need a visual cue to know what just got locked

).