I imagine that Hitler & Mussolini had translators along with them when they had meetings, but if it was just the two of them, was Mussolini expected to speak German or was Hitler expected to speak Italian?
Mussolini was a multilinguist who spoke Italian, German, French, English, and some other languages fluently. Hitler spoke German.
Mussolini was relatively fluent in German and thus didn’t bring any translator with him for their meetings. However, when seeing him, Hitler invariably exercised the customary right of a head of state to have a translator present during meetings with their foreign opposite numbers, even though the conversation was being conducted in German. Usually this would be Paul Schmidt.
In addition, there was a suspicion amongst aides, on both sides, that Mussolini’s German actually wasn’t up to the task and that he persisted, in the face of the complications this got them into, simply out of pride.
Wre there any transcripts of these talks?
Are they available today?
Not that I know of. It’s a fairly common pattern about Hitler’s summits with foreign leaders that one of the sources historians have to fall back on is Schmidt’s memoirs. He was both sitting in on most such occasions, even the one-to-one meetings, and survived the war to publish what he recalled having been said.
Of course, Mussolini privately tended to claim that such meetings usually just involved Hitler ranting on at length about stuff. And there are examples of those sorts of rant, in other settings, summarised in the Table-Talk.