- There are no sub-tags xml:lang="und" and xml:lang="zxx" in your “multilanguage.epub” file. (
https://www.w3.org/International/que...e#undetermined)
- Also, unfortunately, Sigil do not work at all with soft hyphens - instead of OpenOffice. As I understand, “soft hyphen” cannot be inserted into an aff-file as ignored char, so programs have to process with chars like soft hyphen etc. by itself...