I from time to time receive PDF (forms) that need to be filled out. I use Libre Office for this as it’s convenient. But some companies send out their PDFs with fonts not being on my system. I even don’t want to install them.
Why can Okular display the page correctly although the font is NOT on my system?
The document I have has two fonts partly embedded. Okular can make use of them to display the document while Libre Office (for whatever reason) needs to have a replacement font installed on the system and can’t use the embedded temporarily, right?!
It’s not that. If you don’t want to install the used fonts directly (i.e. avoid installing various fonts used by some Windows users, not embedded when creating their pdf and send it to you, or you download it from them) - - -
THEN:
LibreOffice offers their font-replacement table to seek the next matching fonts that are installed on your system. But you have to configure the table yourself.
The way I handle such files is by opening them in Inkscape with the Cairo importer, which turns the glyphs of embedded fonts to SVG paths. If you convert glyphs to paths, Inkscape will correctly open most PDFs. Then I fill out the form in Inkscape, using the Text Tool with one of the fonts I have installed on my system (usually the goofiest free version of Comic Sans I have), and export it to PDF.
The resulting PDF will be slightly larger in size, and the text of the form won’t be editable, but they deserve to get that for sending you such a crappy PDF.