I think I understand your point of view, but I disagree that the "content display" must always be the same as that used by the system.
I consider that the target software such psppire is that the content of the information to be displayed in the same way in different systems. For example, Stata work that way, and set as default monospaced font by default, which allows a data sheet looks exactly the same, independent of the configuration of the system.
For example, when I set the column width of the data in psppire, I do think that my data file with that information is displayed in the same way using PSPP or SPSS, in Windows or Linux, configuring a monospaced font, or same font that I have used at that time.
Another reason is that the font information is not relevant to the content of information, and is not stored in the file's metadata (as they do OpenDocument format files), but if it is relevant to the user, the which manipulates information through the GUI and have to change the application settings (not system settings) to see the data in the same way a different computer/system/desktop environment.
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