The only things I can see that could be changed are:
1. split xstone_wall_clobber into the hatchery column (top row and bottom left) and a 2x1 hatchery floor.
2. x_stone_Wall_chaotic - these are mainly used around the base of the portal when it's surrounded by water/lava.
3. separate that column from the barrack floor tiles. I'm still not sure where that column is used though
4. remove the top row from xground_stone_solid, as these aren't floor tiles
( for consistency with the xground_research/scavenge/training/treasure,
5. xstone_var currently contains a column tile (unclaimed version of xcolumn_claimed_corner( middle top) and the ceiling tile)
(maybe place them in a file xstone_misc with the top row elements from xground_stone_solid)
Beyond that, I'm at a loss