No title for killing normal rag or heroic cho gall
Nixs
They don't normally give out titles to normal mode kills I think unless it's the final boss of the expansion.
As for Grand Empress, it's because she's not the end of the tier. Heart of Fear completion unlocks Terrace of Endless Spring, and the story continues and concludes there. That's why she doesn't get a title. It's not like Nefarion/Chogall in cata, they were separate and unrelated instances that were in the same tier, while this time it's a linear progression. ( I don't think cho'gall had a title anyway if I"m not mistaken.)
Tranquil Master is kind of the MoP version of Champion of the Frozen Wastes or Defender of A Shattered World. I guess they chose to make it an achievement of defeating all the Sha instead of each heroic and end raid boss to highlight the importance of the Sha. Either way Sha is considered the tier end boss so you would probably have killed Empress before him and received the title at the same time.
As far as using the title to determine if someone has killed a boss on normal you can still go to the armory if it matters that much. In most cases if someone has completed LFR you can give a short explanation of the differences, maybe wipe once for experience and then probably kill it. You just have to be lucky and find the right people but you could bring normal mode complete people and still fail because they were carried to their kills.
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