After placing your font textures (default.png, alternate.png) inside the font-folder of your texturepack, the game still uses the default texture files in minecraft.jar. This happens with every texture resolution (even with native res textures).
This is not a feature suggestion, it's a texture-related issue that needs to be fixed like all others too !!!
It's the same as the game would always use for e.g. the default particle textures instead the textures placed in your texturepack, the font textures have the same priority !