First, I'll just quickly say I'm loving ECWolf and the brilliant way it brings modding to life. And Executor's Techdemo is a bloody brilliant mod in its own right. Playing through it, I think ECWolf is golden and can only get better — and I do have some thoughts for a couple of little things that could go a long way.
Definitely not bugs, nor really issues. Just tips for future dev.
First, proper true colour rendering! It'd make 24/32bpp hires textures (which are already supported!) display correctly without the naff palette-snapping and it'd also make the doom-style lighting/visibility thing look a lot healthier. (It'd probably also improve performance, I imagine, since the CPU won't have to be searching the palette for nearest-matches — I'm guessing that's the mechanic, obviously).
Maybe either have an option in the graphics settings to use 32bpp rendering. Or, even, just have a flag to enable it on a mod-by-mod basis. Bah, just an idea.
Also, I'd like to point you towards maybe implementing some "fancier" stuff to the audio in the future. I'd strongly suggest a lowpass filter. With a simple LPF, you could distinguish sounds positioned behind the player. You could also significantly roll off the high end for sounds coming from other rooms when doors are closed. Why not stick a simple reverb in there, too? Here's a tip for the reverb: have a single global reverb with a quiet output level, then have all sounds that send to it send before level-by-distance. That way, very distant sounds will be wetter reverb-wise than closer. Also, modders could specify the basic reverb parameters on a level-by-level basis. On the subject, "Freeverb3" might be worth looking at if you're ever interested in jazzing up ECWolf's audio.
Sure, these sound like things that would drift from vanilla. Vanilla's fine, but ECWolf has some good features that could also modernise it a bit (hires textures, widescreen support, sound mixing, etc). And there's nothing wrong with giving Wolf3D a facelift — it'll show kids today why it's better than the visually-superior but otherwise naff rubbish they're playing now! :-)