About [[EtherpadLite:Timeslider.unnamedauthor/en]] and [[EtherpadLite:Timeslider.unnamedauthors/en]]
This is an invalid implementation of Plural. English and some other languages have two forms, but many language have multiple plural forms.
Updated our i18n lib, so this should be possible now. See https://github.com/ether/etherpad-lite/pull/1841/files for an example of how it works and https://github.com/marcelklehr/html10n.js#pluralization for a thorough explanation.
That's pretty awesome. In your documentation you mention "zero | one | two | few | many | other [..] as specified in the Unicode rules". Could you link to the Unicode rules? I assume you mean these (http://www.unicode.org/cldr/charts/supplemental/language_plural_rules.html ), but I cannot be certain.