Is there any way to customize codecs for any tile editors? The only tile editor I've found that has nearly the right codec for the game I'm currently translating (Summon Night: Swordcraft Story Hajimari no Ishi) is YY-CHR, and the codec is "1BPP 16x16" - however... It's a bit off for a small reason. The tiles are 12x12. I've tried messing with the font a bit in YY-CHR using 1BPP 16x16, but in the end, it's too confusing due to the difference.

Secondly, there's a small possibility I'm mistaken and the tiles are slightly off. It looks like they COULD be 12x16, although that would be a bit odd.

Finally, I'm really sorry if this is a stupid question. It seems to me like this shouldn't be too hard to change, but I didn't see any options in any of the tile editors I've tried.

Edit: For a bit of a better explanation, here is why 16x16 isn't working:

The part of the character cut off the bottom of the tile is in the top of the tile to the right. With my current plan, I'm going to have to edit a very large amount of the characters in the game, and finding the exact top, bottom, left side, and right side of each 12x12 space for a character is way too time consuming.

Thanks for the help. Tile Molester didn't have the right codec, but I'm setting up FEIDIAN right now. Odd for it run in PHP.

Looked at Angelique, and it would be way too time consuming. As far as I can tell, it doesn't even have a go-to option, and scrolls 100 bytes at a time. The editing is worse for the amount of tiles I'm going to need to change.

On FEIDIAN, I'm having trouble. Installed PHP, but when I run it I'm getting no results. I set up a bat file with the following line:
php feidian.php -cr snss3,12,12,16,16,0x14d5a80 rom.gba output
but all it does it print the entire contents of feidian.php in the window. (I have a copy of the game in the folder called rom.gba by the way, so it IS supposed to say that.) If I remove the "php" and the ".php" like it says in the readme, the command prompt says it's an unrecognized function.

I had this issue for a while too. I think I fixed it by manually installing a different version of PHP (specifically one in the 4.x versions, maybe it's incompatible with 5.x).

Extract this into the folder where Naga is located.

Sliver X: Thanks for the help, but Naga doesn't seem like it's going to help. 5 minutes of scrolling got me 1/5th of the way to where the tiles are, and clicking Go To crashed it. Twice.

On the side of FEIDIAN, I finally got that to work, but now I'm still not making much progress. I have no idea what pattern 1bpp uses, so it's impossible to output 1bpp 12x12 any other way than trial and error, and I have no clue what to try next. Does anyone know how 1bpp works? 

DjinnTileMapper does 12x12. Actually it'll do anything from 1x1 to 16x16 selectable size(independent X and Y settings ).