At the moment I've got little to no time to work on this, so don't expect any updates before next week.
As you noticed, the coordinates in the subimage file are a little off at times. It is strange that the selected font colour does not apply. I'll look have into that.
Exporting to PSD is an interesting idea, although I'll have to check how complex that format is.
With the new rendering method, the next version will also have a completely different UI. There are several more effects planned for the future. These include more options for the drop shadow, outlines, textures, and reflections.