This addon is exclusively for mechanics found in dungeons, trials, and arenas.

When you dodge roll, you gain Dodge Immunity for 1 second. For attacks that connect instantly (i.e., melee attacks), the red line is 1s before the attack lands (the red line is at 0.8s for projectile attacks since they don't connect instantly). Dodging before it reaches the red line runs the risk of the attack landing after your dodge completes. The area between the red line and the end of the bar represents the recommended window of opportunity for dodging.

For the dragon breaths, if a tank dodges during the breath, they run the risk of a tick of the breath landing on them during the brief window of vulnerability after they exit dodge immunity and before they regain block or start the next dodge. However, if a tank dodges the final second of the breath, they don't run this risk and they avoid the final--and most painful--ticks of the breath. The line, as before, marks the start of the recommended dodge window.

As for the heavy attack on Yolnahkriin, that is an issue where the animation for its heavy attack can be delayed by about 0.8s at times, which results in the heavy attack damage landing mid-animation. This is purely a problem of the animation being delayed. And yes, the dodge timer for the heavy attack is accurate, so I recommend timing dodges of Yolnahkriin's heavy attacks based on the addon's timer rather than the in-game animation.

The latest version of CCA does alert the shatter dodges with a timer bar. However, shatters have a very short cast timeof only 0.7 seconds, so there's nothing that I can do to provide players with a warning longer than that.

If this is happening after the first flight phase, that's the correct behavior.

The reason is that the first flight phase is shorter than the second and third flight phases. If Group 1 was called shortly before he flies (which is a common occurrence in HM if the group is playing it safe and killing atros as they spawn instead of saving them for flight phase), then by the time he lands and starts casts tomb again, the people in Group 1 will still have some time remaining on their 60s debuff, particularly since tomb usage in HM is typically staggered.

In this specific scenario, the counter does not reset and will call Group 2 instead of calling Group 1.

Raid Notifier and versions of CCA prior to 1.4.10 (which was the version where CCA started to account for this scenario) will always reset after a flight. CCA 1.4.10 and later will almost always reset after a flight, but will make an exception if necessary to avoid the scenario described here.

Raid Notifier handles that.

That sounds like a lag issue.

CCA does not alert poison. That's Raid Notifier.

Raid Notifier already handles those mechanics.