The machine writing a drawing need not have the font the drawing will be opened with. `systemfonts` substitutes without saying so, and the plot is then laid out with one font's widths while the drawing asks the spreadsheet application for another. Often that costs nothing, because some substitutes exist to match: Carlito for Calibri, Liberation Sans for Arial, Liberation Serif for Times New Roman. Others are unrelated fonts of quite different width. The device does not check, so call this when a drawing's layout looks wrong and you want to know which font produced it.