Hey cool, do you have a link to your game ?
I don't want to mix images (some from my pixel artist, some from opengamearg.org), because most players would complain the graphics are inconsistent. There's momentum with each release and I don't want to ship a half-baked game.
Regarding mixing letters and graphics, the two backends are distinct; I can't mix both. The letters aren't graphics: I really am drawing text using a bitmap font; so the code differs from drawing graphics.
If you want to have access to early builds, I can add you to my list of betatesters, to which I usually ship versions one month or more before an upcoming release. Would that suit you ?