I have looked at these maps, and I have found Drakona's "Valor" map to have a couple of geometrical errors stretching the D1/D2 engine in a way it doesn't like. You cannot build triangular sides there (you can for the D2X-XL engine). I have created a fixed version of that level. The level's lighting also was completely off, at least when viewing it with D2X-XL. I have fixed that, too. If you are interested, I can make it available here. My version of that level will also work with other Descent variants using the original "baked in" lighting.
"Antbend" also has a lighting problem in D2X-XL. I have fixed that too. That fix also is backwards compatible.
"Arising" has a misaligned (overlay) light texture and could use a few less lights imo.
Ditto "Dukebox". Dukebox also has two degenerate segments (cubes - I prefer to call them segments, as they can be quite different from a cube or cuboid); They are completely flat and can be removed (which I did). Hint: Using DLE's diagnosis feature during level construction is always a good idea.
I found that Dukebox looks much, much darker when using "basic" or "standard" lighting in D2X-XL than it does with lightmap based lighting. The reason for this is that it uses the energy field wall texture and the blue and red light stripe texture as base textures (i.e. not being glued on top of another texture). D2X-XL's lighting considers such lights as intended to only light the segment side they sit on. D2X-XL v1.18.57 has this fixed, but light textures should nevertheless generally be applied as decal to a base texture. This will make D2X-XL produce a glow effect for them (if desired; light glow can be toggled in D2X-XL's effect options dialog).
Here's the link to the archive with the missions I have modified: http://www.descent2.de/files/missions/3 ... st_2015.7z