Yea, this was my interpretation as well. Even then if you do take damage from the one consecrate tick immediately after vanish, it won't pop you out though you still take damage. Once that immunity-second fades, the next consecrate tick pops you out of stealth.

Sounds like its working as I understood it, but I will agree that they could try a little harder to nail down the one full second rather than chopping it short...

In re your edit - in your AoE example the first tick of consecration, which occurred in the immune second and did not break your vanish, a second later, it ticked again, now outside your immune second and broke your stealth. To prove it is not working as intended, you need to show that the last tick of an DoT or AoE, which ticks and fades during the immune second would result in you being unstealthed when the immune second expired. You haven't done this,.

They are reported as fading before the consecrate damage is reported, but the combat log, as far as I am aware, only has a granularity of 1 second, so you can't assume anything about the precise order of things that happened on the same second. Better to do the actual test.

I routinely gain profession skill ups before the item is created in the combat log. I also routinely gain them afterwards. The log is not precise enough to tell you which tick brought you out of stealth. I would say if you manage to avoid a projectile that is already fired at your position simply by popping vanish, then it is clearly working way better than intended.