Thanks for the comments. (... and sorry for the late reply, lol)
First and Second: It's intentional, I obviously tend to avoid this too, but it seemed like it would fit in this map.
Third: The shadow is also intentional to make it look like the ground is lower than the one next to it. The second does look a little weird and I probably could've chosen a different tile. As for the third, I really don't know, the borders were a tiny bit confusing to work with back when I made this, pfft.
Fourth: I mean... it's just supposed to be a big river. xP FE7 17 did this too, but it's different tiles which is weird because I couldn't find the ones used in there. Maybe I'm just blind. I guess cliffs would also have worked.
Fifth: This was mainly just a test to see how far I could go with mountains, I think. If I wanted to make it more of an open field I'm pretty sure I would have, pfft. And yeah, the backwards cliff/river tile looks weird but it's also weird if there's only the not reversed ones on the map.