Water sometimes cuts horizontally though the map when its compiled but its supposed to fill the brush volume with water. I dont think there is a perfect solution but i would try one of these.
Make sure it has structural brushes around it to define the boundaries.
Try using a no_draw_decal brush with water texture on one face.
Terrain patch.
Curve patch.
If none of those suggestions work i have a dynamic water texture and a scrolling foamy texture/model i used for a waterfall and stream i might be able to upload.

Did launcher compile your map before?
Does a new script placer map without any edits compile and load?
Are you running as admin?

If you send me a pm with a mediafire link to your map I will fix it.
You can also probably fix it yourself by doing these in radiant.
Fix any red or "node without volume" errors from launcher.
Caulk faces of unseen brushes.
Look in the radiant 2d view for brushes that are not snapped to grid or aligned with another brush.
Make sure no brushes are intersecting unnecessarily.
Make all stairs and railings into detail brushes.
Mitre edges of 2 touching brushes when possible and caulk the unseen faces.
Fly around under the map and look for any mapping errors or brushes you forgot about.

Entity 0 Brush 2413 at 7330 -2511 321
Go to the brush or patch and fix it.
Its could be a cylinder patch twisted, a terrain patch that is folded onto itself or a bad brush ect.

Add deathmodel to a csv if you havent already. Check appdata/.../mods/mapname/missing_assets.csv for anything related to your vehicle, ignore everything else in it.
If the rotation happens after death you can get "classname" "script_vehicle_corpse" and check the targetname to be sure its the right one but you cant use functions like rotate on the corpse so you need to spawn a new script_model at the corpse.origin, delete or hide the corpse, rotate the script_model.
Another option would be to give the vehicle (X*2) health and in gsc wait until (X) dmg was done, rotate the script_vehicle or use a crash animation then kill it through script.
If you need a gsc example for either i can upload one in a few hours when im home.

Your map has a leak but your actual error is missing assets.
Make sure your game is updated. Check ugx wiki.
Make sure your modtools are updated. Check ugx wiki.
Press the converter button in launcher.
Create map with a script placer.
Compile your map, map_patch, then mod using the settings from the ugx wiki.

Post a sample of the data.

You should be able to do almost everything in blender with codwaw import/export by codemanX.
Make sure images dont have an alpha layer(transparency).
Precache model.
Include model in csv.
Include images in mod folder.
Update weapon file in mod folder/csv.
Use 3rd person dvar to see if the weap model is behind players view or above the players head.
Check asset manager for correct settings.
Look in TomXmodel utils to see if custom model has a texture and has the correct position of the original stock model.
Check console for missing stuff.

Does a new script placer map without any edits or custom stuff work?

2 materials 1 texture.
You can separate the trunk from the canopy/branches/leaves in maya and make another gdt model_phong material for the trunk/bark but still reference the same texture file as the leaves.

If the grass and tree models i sent worked you could try duplicating my gdt entry with the copy/paste/duplicate buttons in asset manager.
In radiant the tree leaves usually are multicolored like the stock trees but ingame they will look normal.
If they are script_models they probably receive light differently or need the "ground lit" option in asset manager but I'm just guessing.
You can send me a model and texture and i can convert and try if you want.

Convert materials then models, add images from raw images to mods/mapname/images
In mapname.gsc add dvars above or below zombiemode::main();
]https://www.mediafire.com/download/uu74znaxj57j0fg

After changing the material to dynamic foliage or tree canopy the models need to be reconverted, it should print "dynamic normals generated" or something like that when converted.
If that doesn't work you might need to delete and remake the gdt material entry if the original material settings are sticking.
//
I can upload a gdt/model/texture if you dont figure it out.

In asset manager (at the top)
materialtype
"dynamic foliage" or "tree canopy"
//
These might be needed depending on the purpose of the material
Surface properties (at the bottom)
"Noimpacts" "nomarks" "transparent" "nocastshadow" onlycastshadow"

You need to edit the name in the ugxmod.iwd/maps/zombiemode_weapons.gsc