All the LOD meshes should be at the same place in the hierarchy, so leave them unparented, unless the mesh is supposed to be a child of another mesh.
Also, I tried writing LOD in capital letters, but I couldn't reproduce the errors you're getting with Blender 2.79b.
After taking a quick look through the game files, it looks like DOCK chunks are a feature of the ship files, not the mesh files. I have no idea what DOCK chunks do or how they work, and Wing Blender was designed to export mesh files.
As for the performance boost, I don't think it has anything...
With my most recent optimizations, I was able to cut the import time in half! Well, at least for the more detailed meshes. AST_S_01.IFF hasn't shown much improvement in terms of import time, but that's because the other bottleneck is the MAT reader, and I have no idea how I could optimize the...
It's been a long time..
Anyway, if you've tried to use the importer, you'll know that it is sluggish as hell. I've been trying to work on that. I made a few optimizations to the importer recently, which mostly involve using flat typed arrays instead of lists of lists, and it turned out to be...
This looks like something completely different than Wings of St. Nazaire to me. BTW, would it be possible to see a GNU/Linux or browser version of this game?
I wrote a Python 3 script, and a C++ program, to convert the WC2 CEL files (the ones that can't be converted to PNG using ffmpeg) to PNG.
The Python script can either work as a standalone script, or within Blender by moving it to the addons folder.
The C++ program requires libpng 1.2 or higher...
According to this page, the CELs are just FLCs. I was able to convert most of the CELs, except for the WC2 ones (with some unfortunate input/output errors, but that didn't seem to be a huge issue) to PNGs using this FFMpeg command line:
ffmpeg -f flic -c flic -i WHATEVER.CEL -f apng -c apng...
I also noticed something weird with AST_H_01.IFF when I opened it up with a hex editor.
The SPHR chunk should be 16 bytes long, but it is only 13 bytes long for some reason, and has "SPHR" at the end.