I'm going to go out on a limb and suggest that at least the G7 support staff or the NATO nations based on a modicum of trust got together before the dinner and coordinated which translator each country should bring to the dinner covering as many permutations and combinations as possible and so...Canada did not bring the French translator nor did France bring the English expert!

It appears the USA offered the English/Japanese expert so it begs the question who in the G7 or G19 provided the alternative Russian/English/Other language translator?

Perhaps Melania convinced Donald that her own command of Slovenian and Serbian would permit her to converse with Vladimir Putin...and from the film clips it appears Vlad was wholly engaged and that is perhaps why Donald was threatened and went over to intervene...the rest we will have to wait until the Russian translator moves to a safe haven and writes a book!