After closely comparing your letters file with the custom letters and template file that I made for End of Ages, I found what the problem in your image was Tony.
Because you setup your inside edge with a dithered transparent pattern, you needed to change how you tiled your image to account for that. What was happening was that on one of your edge tiles, the dithered transparent pattern was going one way and on the other edge tile, the pattern was reversed. Graal was then loading both dithered transparent patterns on top of each other and since each was the reverse copy of the other one, they appeared filled in where they overlapped in the textbox.
Download the fixed version that I made for you right here.
KyleOdin-TonyLetters-Fixed.png
There is still an ever so slight glitch in your transparent pattern around the bottom corners where I fixed it, but I highly doubt anyone who is not trained to notice minute differences in images would notice it at all. ;-)
Heads back to working on graphics,