I also tried some mapping and I used those Cave borders you are using, but jees they are a pain in the ass at the first time using them.
Yea that@LordVissie u mean red mountains?
Figured I'd add to your little diagram here with the correct variation of borders to use in this theme (To avoid the bug everyone has experienced atleast once)
You are*Ur really good. Keep going
nub.You are*