Calling it "the world of warcraft" just means the Titans see Azeroth as a world where wars are typically forged, which is true.
Also, have you ever taken into account that MAYBE Chronicle Volume 1 had no way of documenting the whole Titan spirit thing? I always liked the theory that the Legion stole the Titan spirits during their assault on Ulduar early 7.0.
Besides, Chronicle does release before Legion, so Blizzard could always add that as an in-universe reason for why it was never talked about.
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It's okay.