I noticed that in the standard installation of LibreOffice on Ubuntu 19.04 there are some bundled fonts missing that LibreOffice uses in some of its standard templates. For example, the bundled Impress template “vivid” uses Adobe’s Source Sans Pro (which is openly licensed as OFL 1.1) throughout the whole template. Since Ubuntu does not packages this exact font LibreOffice has to substitute the font and moreover is hinting this only by showcasing the font’s name in italic. Not very user friendly.
This is true for many of the bundled Impress templates and clearly not optimal. Users are most often not aware of the fact that the font displayed is not the font indicated in the menu. And creators of LibreOffice templates cannot rely on LibreOffice’s bundled fonts for making sure that their template is correctly displayed on all three platforms (Linux, Mac Os X, Windows). I would therefore suggest that Ubuntu packages exactly the same fonts as the Document Foundation foresees for their binaries (or at least the fonts used in templates shipped by default): https://wiki.documentfoundation.org/Fonts