The errors are mostly Skybox related.
in some of the maps you add F_SKy1 to the ceiling and floor. but with the walls you forgot to set them to line horizon, so the walls arent messed up.
There is also an error MMROBO2 (the crusher) where in the Buildings part, everytime i go up the floor seems to come up with the sidedefs but the floors stay there (i hope u know what i mean).
and in Treasure trove Cove, there really isn't a lot to do in it, besides the underwater part.
And a suggestion: In Rusty Bucket Bay, Add Deepwater in the dummy sector to make it feel llike your really in oil (you can make it brown underwater too).
I do not mean to offend, if you want i would be happy to fix the skybox problems with some of the maps, if you wanna'.
these are really nice maps, MAKE MOAR

!