On behalf of the German language, I dare to say to my favourite all things sci fi blog io9: You are welcome.
[...] another Star Wars: Episode VIII mystery has been answered—namely, whether The Last Jedi refers to a single Jedi or a group of Jedi, since both the singular and the plural form are “Jedi.” The solution comes to us via the release of several foreign-language titles for the film.
Thank you, other languages who modify their adjectives to distinguish the quantity (and gender) of the nouns they’re modifying!
Indeed: Otherwise it would be: "Star Wars: Der letzte Jedi", or, if female: "Die letzte Jedi"; unfortunately we do not further separate male and female in groups, so "die letzten Jedi" may be a group of only men, only women or a mixed one. Spanish is e.g. helpful here, as the correct title would be "Las últimas Jedi" in the case there would be only women-Jedi left. As in other european languages, the male form is used as a generic form aswell, so they may only be men but also a mixed group according to the Spanish title. But this, I think, we knew already after seeing Rey and Luke in Episode VII.