It's strange that the base and extended fonts have different sizes. I'd expect the correct size to be at 16px. I'll look into it and see if anything went wrong in the export.
As for missing characters, monogram.ttf only has 104 glyphs: unaccented upper and lowercase letters, numbers 0-9 and a few common punctuation marks. For Ü, you'd want to use monogram-extended.ttf.
Thanks for letting me know!