Well the main goal of your HP edits AFAICT is to make the brighter, more colorful, lighthearted films (the Columbus ones and to a lesser extent the Newell one) more in line with the darker, more drab, “serious” (no pun intended) films (the Cuaron one and the Yates ones). You keep comparing your take to LotR, but I don’t recall any scene in those films looking like sepiatone the way your second clip here does. Look at the color of the Shire! And even in the darkest time, on Mount Doom, there’s still a thousand times color than in anything Yates ever directed.
Seeing this thread being posted reminded me to buy the full Blu-Ray set (I only had DVDs of 1-4) to make edits of them that are just the opposite, so I went and did just that. Now I just gotta rip 'em and get to work. Granted, I should probably rewatch them first. I guess I could do that once I finish Series 1 of Doctor Who, which I just started. Still, I could do some preliminary work on things like color grading, openings, and credits. I’m thinking of watching the extended editions for my rewatch so I can see everything I have to work with in action.