Welcome to the wacky world of Adventuron's weird scaling. No matter how hard I try, I can't make sense of Adventuron's scaling algorithm. It tends to snap to unexpected sizes in the most unusual situations. All I can suggest is experimenting with the horz_pixels, vert_pixels and experimental_line_height_ratio values in the fonts section. I have no idea what the first value does. The second one seems to affect the font height, but sometimes in a completely unpredictable manner. The last one affects the leading, i.e. spacing between lines. I'm using a Google font and values of 8, 15 (or a bit less) and 1.2 respectively work well for me. Prior to this, I was using a bit-mapped font and values of 16, 16 and 1.2 respectively worked well. If you're using any of Damien Guard's fonts, values of 8, 8 and 1.2 generally work well.