Working on their Cover
The acolytes are, naturally, working undercover. Rather than simply having different names to use, which often causes problems of its own, they are pretending to be noble cousins from a different world. Fenksworld, in fact. Thinking that they are from Fenksworld is causing its own problems, though, mostly them trying to work out if they are actually from Fenksworld or just pretending to be from Fenksworld. It really shouldn't be this difficult.
Their cover is explained more than a few times, somewhat complicated by them having to maintain their cover whilst understanding that it is, in fact, just a cover. The acolytes' companions are taking them to a party with other nobles, and so tests their understanding.
'Oh, you're from Fenksworld?'
'Yes.'
'Really?'
'...no.' Oh, so close. It was a test! He was not being suspicious, merely curious, as so few people come from so far away. Which, to be honest, is the reason why Fenksworld was chosen.
And with this last test explained, if not fully comprehended, the acolytes are taken to the party.
Dariel is posing as a noble, although he'll argue to anyone who'll listen that he actually is a noble, making his cover pretty good, with Matthias in his entourage as his bodyguard. Again, this is just their cover, but it's easy to forget.
The last-minute training is paying off, barely, as Dariel tries to integrate himself with the other nobles, hoping to find out information about the Joyous Choir and maybe get invited to their higher echelons. 'So where are you from, originally', he is asked.
'Venksworld', he replies confidently.
'Sir', his fake bodyguard interrupts, 'I have an urgent security matter', which is pretty much the only way a bodyguard can speak without first being spoken to. Matthias pulls Dariel aside before continuing, 'we're actually from Fenksworld, with an 'f'. I'm sorry to correct you, but if I hadn't I fear by the end of the evening we'd all be from Venezuela'.
The curious pronunciation is put down to Dariel's heavy Fenksworldian accent, and he even passes the 'really?' test, letting the evening continue smoothly.