I have to say, I love what ESO is doing with Coldharbour. Representing him as the God of Schemes was just a PR-move, true. Though it is technically accurate, it is indeed pushing the issue of his sphere's true center to the side. But I'm not worried, because they can't abandon Molag's core sphere of domination and rĂ¡pe and slavery and corruption and so on, his core sphere of insatiable greed and desire. If they did, they wouldn't have any content. And if you take a good look at the public information and what we can discover from leaks, his actions and intentions in ESO fit his sphere perfectly. Even the detail of dragging Nirn into himself is fitting: Invading Nirn in the same manner as Dagon or even approaching and directly enveloping Nirn would be out of character.
And, as an aside, in regards to conflation with Boethiah, their Schemes and Plots are very different. Molag Bal's scheming is scheming to retain and gain power, the sly plans and traps set by the paranoid king and the greedy merchant. Boethiah's plotting is scheming to take power from others, to fell kings and leaders and so on. Their scheming and plotting are centered in their spheres proper, directed towards very different goals.
Regardless of past descriptions, Coldharbour in ESO looks spectacular. You have gloomy skies and streams of soul-white water and complex magitech machinery and so on, and it is all so very fitting, so very interesting, so very cool. In my mind, if a new representation takes a more interesting spin, the new representation takes precedent. Apocrypha wasn't originally presented the way it was in the Dragonborn DLC. The details match, but who honestly originally imagined it as the tangled (and beautiful) mess that it was portrayed as rather than as a neat, endless library? Apocrypha's original description even notes shelves; do you remember seeing anything you would describe as shelves in Skyrim's Apocrypha? Yet Skyrim's Apocrypha was much more interesting than the original image. I'm more than happy to replace the original image with the new image in the case of Apocrypha, just as I am in the case of Coldharbour.
However the rest of the game turns out (I'm staying optimistic about the factions, but there are always the scattered Ayrennesque details getting in the way of that), the Planemeld and Coldharbour look to be turning out great. I'm excited to learn more about them, and about the Soulless One.