I don't use skill/spell ranks in my game...Its damage clearly scales w/ the player as they grow...Thus, I made it so INT also increases MP costs.
Another obvious solution would be to simply not gain additional MP as you level. I've played other games that did this, and TP already functions like this.
It might feel more sensible to the player for the system to scale that way, rather than saying "This skill you have costs more resources and it's beyond your control."
Just getting back into RPG Maker after a long absence...Even so, I'm happy with how this turned out.
I think the map generally looks good. The thing I would point out is that your wall heights vary between 2 and 3 squares, which makes things look wonky.
If you have walls of different heights, you should have other elements making it obvious why - like the right half of your north wall, you have tall walls but at one point you have a ledge halfway up. We can see that's a tall cliff with other stuff coming out.
But if you start at the entrance in the middle of your west wall, that height is 2 squares, then following it north the outcroppings are 3 squares tall. That looks stretchy and weird because we don't see anything else in that area indicating the wall is going up a hill or anything.
And then a lot of the rest of the map along the south side has 3-height walls. To me, seeing a taller cliff stretching off the north of the screen makes sense, but if we don't have any way to be on top of the southern shapes and seeing difference in terrain heights, there's no point in making those walls taller - I'd suggest sticking with your 2-height.