This is because the language "de" specified by the website isn't getting mapped to the right hyphenation pattern, which is installed as hyph_de_DE.dic (we're using our own hyphenation patterns installed via the language selector rather than the ones bundled with Firefox). The upstream hyphenation pattern is installed as hyph_de.dic
This is because the language "de" specified by the website isn't getting mapped to the right hyphenation pattern, which is installed as hyph_de_DE.dic (we're using our own hyphenation patterns installed via the language selector rather than the ones bundled with Firefox). The upstream hyphenation pattern is installed as hyph_de.dic