Welp, part pf the campaign cash deal.
No one else probably means no other govt. officials, but translators should be assumed.
Translating isn't easy on the fly, and they would have to have a specialty in diplomatic affairs, seems to me.
I don't believe any head of state would communicate in with another head of state, in an official meeting, in a language they weren't completely fluent in; even then, mother language insinuations may not be fully understood.
Trump, for example, with all his references to US history and sports, would be hard to translate for a person whose mother tongue was not US English.