Thanks for the template file and sample PDF documents.
For your information, in Excel to PDF rendering, it is necessary that the fonts (.ttf files) used in the spreadsheet should be available in the operating system’s default or specified fonts directory.
Please note, regarding font substitutions, by default, Aspose.Cells checks the workbook’s default font to see if it can be used to show the text properly. If not, Aspose.Cells will search all the fonts in the specified folders. Aspose.Cells APIs also provide the ability to specify the substitute font for rendering purposes. But this mechanism is not always helpful as it might deteriorate the formattings. For your information, every font has its own chars’ glyph and cannot be matched with other font.
To cope with your issue, as I told you earlier, please install the underlying fonts used in the workbook (in your case, please install Arial and Calibri font files (.ttf files)) on linux, it will work as expected (same as the output on Windows).