Nooooooooooooooooooooooooooooooooo
I'm trying to remember if MazzleUI itself (i.e., the "core" of it sans Mazzifier) has anything in it that will break. If not, you may be in good shape as long as you update the other mods to LK-capable versions. Nothing springs to mind, to be honest, though I can't speak for the configuration (some API signatures changed, notably the dropdown api -- not that it's hard to fix (usually just swap the object to be the first parameter) if you're adventurous).
I got started with my project just trying to make an interim "something" to work with after the last big update -- turns out MazzleUI was updated enough and I didn't have to use it but I'll tell you what I did and it wasn't that hard or complicated.
I originally just replicated the backplate with eePanels and the MazzleUI artwork (I still find the original MazzleUI backplate graphics to be the best I've yet seen) and used Pitbull as a unitframes (DUF may still work, for all I know; I know another author had taken it over but I haven't seen an LK update) which was annoying but workable in a pinch. It's even fairly easy to do the target panel with eePanels. I even went so far as to use eePanels to do part of the HUD display that DUF did and the MazzleUI hotspots
None of it was terribly complicated and just about anyone could do it. It's not at all the same but it'll get ya by in a pinch.
What I realized was that I was swapping dependencies from MazzleUI/Duf to eePanels, etc and I just wasn't happy with it so I started my own project which I'm utterly happy with (for
once... and only have w dependencies: on Dominos and Model Citizen) but I have to admit...I just couldn't improve on MazzleUI's unitframe layout, hotspot ideas, or target and charm buttons. Those ideas were so rock-solid cool on a stick I couldn't imagine not re-implementing them. Sad part is, unless you look closely at the unitframes or the active-button layout, it'd be easily taken for MazzleUI. But take it as testament that I know both how much you're hoping for a LK-capable version and how hard it would be to swap to something else.