Linux Libertine has a variant include in LibreOffice: Linux Libertine. The Wikipedia/MediaWiki CSS (checked on English and Chinese Wikipedias) use “Linux Libertine” as the font for headings, then falling back to Georgia. I use Windows 10, which added this version of Libertine fonts after I installed LibreOffice (which is a free, open source office suite works on both Windows, macOS and Linux, also wider spread among most popular Linux distributions). To prevent confusion, this folks use a ‘G’ suffix on its Graphite offerings, that is the fonts are named as “Linux Libertine G.” So, even though I have LLG fonts on my computer, the CSS forces Georgia.
Ideally, the CSS should use “Linux Libertine G”, “Linux Libertine“, Georgia, serif; as the rule. This is compatible with former TTF one.