Longer string for FileSize.B/MB/GB makes the UI ignore half of the file's download/upload progress info.
Increasing the minimum character inside UI makes further issues, so the best choice (Which is already made in other languages like Arabic) is to use a short form.
Visual sample: https://telegra.ph/%D9%85%DA%AF%D8%A7%D8%A8%D8%A7%DB%8C%D8%AA-vs-%D9%85%D8%A8-12-22