In 45+ years of playing/repairing/modifying/building guitars, I don't think I've ever come across one that had tuning issues due to the neck meat. Not even on the cheapest $25 student acoustics made out of toadshit and wax paper. It's always the tuning pegs, nut, strings or bridge. Always. I mean, every single time.
Now, necks will move on you. Environmental changes will affect some neck woods more than others. But, that's a slow change. It'll tune just fine during that change. It'll just get gradually tougher to play over time, or start making noises you don't like as the neck geometry changes. Even that isn't etched in stone, though. Get a neck with a dual-action truss rod, and those things are as stable as the Rock of Gibraltar. That's not a tuning issue.
Wenge is a lovely neck wood with a feel and tone like no other. My only criticism of it would be that it's a wildly open-grained wood, so it has a tendency to collect... stuff. Think of your fingernails, and what kind of various unidentifiable kukka can accumulate under them over the course of a few hours or a day. Same thing happens with Wenge. Skin oil, dead skin cells, dirt, sweat, distilled beer, sneeze residue, hooker dust, staph, strep... who knows? It all accumulates in those nooks and crannies and there's not really a good way to clean it out.
So, keep you hands clean, don't let anybody else play it, and enjoy a fantastic neck.
