Let's talk about Language
Jonathan Harker is an Englishman from Exeter. As such he speaks (Devon-accented) English.
He has mentioned a couple of times now that he also speaks German, but not very well. He calls it a "smattering" but it's enough to get him through Hungary, which is famously diglossic. He does not speak Hungarian. When he gets into Romania the language barrier becomes more profound because not only does he not understand any Romanian, the locals don't have a whole lot of German either. When he talks to the innkeeper's wife they're both using a common language neither speaks well.
You've all heard me go on about this but I am going to say it again: I'm obsessed with the fact that in earlier drafts when the Count was located in Austria he specifically requested a solicitor who did not speak German. He's not supposed to be able to communicate with the locals. He's supposed to be wholly dependent on Dracula, who as we've seen in the finished version is arranging all his travel and writing him little letters and such to help him navigate his way there.
[Aside: is Dracula speaking German to the coachman? Because Jonathan is able to understand their conversation, which he wouldn't if it were in Romanian. It makes sense because the coachman refers to him as the English Herr. But if so Dracula must be doing so specifically for Jonathan's benefit - otherwise he would be using his own language.]
But! At some point Jonathan acquired a polyglot dictionary! This is another great character moment. Like his research at the British Museum, it means he is aware of his deficiencies (not speaking the local language) and taken steps to correct them. Dracula wants him isolated, but Jonathan wants to know things and talk to people. He asked questions of the waiters in Budapest. He asked questions of the innkepers in Bistritz (who suddenly forgot how to speak German). He can't ask questions of the townsfolk or other passengers on the coach because he doesn't speak their language, but he's trying to understand anyway by means of the resources he does have - the polyglot dictionary. Communication is key and he's trying to make it happen.
A second aside: people have pointed out that he misspells (and mistranslates) ördög. Other people have pointed out that he's remarkably good at looking up words in a language he doesn't speak just on sound. (To harken means to listen and pay attention - his name means Listener, so maybe he's just preternaturally good at that). But he's writing his diary in shorthand, which may not have an obvious way of rendering the diacritics (he leaves them off of mămăligă as well) so that's an extra layer of translation. And he's relying on his little dictionary, but that dictionary may not be reliable, in the same way that despite all his research he was not able to find Castle Dracula on any map. (Maybe it's like Rokovoko - too real for maps).
We laugh a lot at "I must ask the Count about these superstitions," but here's the thing: the Count speaks English. No one else on this trip is able to communicate with Jonathan in his own language (or in theirs!) even if they wanted to (which they often don't, since vampires are Scary). And this is by design!
And Dracula speaks excellent English. Better than Jonathan's German. And he wants to get better at it (which is totally reasonable). But there's this huge linguistic power imbalance here, in spite of which Jonathan still manages to arrive better prepared and better informed than he is supposed to.
By the time Dracula arrives in England, will he be speaking with a Devon accent?