Yes you can use 3DS rom tool to see the region of a game. I doesnt say Game Region or [E] but you can check it under min firm (or something like that) and it says the minimum firmware needed including the letter of the region of the game.So is it possible to look up a ROMs region? Does the 3DS rom tool allow you to see it is European or American? Cause I downloaded a lot of both without knowing Region Free Roms didn't work.
For example Mario 3D Land looks like this
"Min 3DS Firm: 2.2.0-XU"
That U at the end shows the Region.