Can't delete, just say you figured it out, and post how you figured it out,

Your walls aren't on the walls layer.

They are on your Level - 0 layer.

And when I try to add a corridor, they want to go to the same room, not other rooms.

Only the lower right circular room is on the correct layer and sheet.

Back on my computer.

Under options there is a []Disable random transformations

make sure that isn't checked. I've done the same thing using other symbol sets.

Under CC3+, overland types, select the word Trees.

There are CocoPalm, overhead. 5 different.

PalmTree, one

palm aa1, etc. about 5 of those.

some grayish ones, all overhead. 6 of these.

some darker ones, all overhead, Palmsurf 6.

There are several further down in the same fsc that are just named Tree and a number. 3 of those, also overhead.

Easy to find if I get told what set they are in.

Those are in CSUAC/DA Vegetation

They are called 'Jungle Tree'.

I found side view and vari-color in:

Profantasy\CC3Plus\Symbols\Maps\CC3\vegetatioon.fsc

Tops, entire trees, etc. Not sure they are palm, but they look like it to me.