The MS translation is slightly different, but it does make me interpret the chapter differently. Yes Julius face was odd as usually he appears somewhat goofy, which is just the result of him being confident he has the situation under control. He also always gives the impression he knows everything, but pretends he does not. So yeah for him to show that kind of expression indicates something is happening outside his comfort zone.
Now in the JB version Aster is just wondering about what he is sensing, but in the MS version he recognizes it from somewhere. Now I already found it strange that Rangil said he would use his grimoire's magic. It indeed seems he just now opened his book, but still it remains a weird concept as no other character has ever acted or said something along those lines.
But what if there's a demon inside the grimoire and it's that he's referring to? And that Aster recognizes the feeling from the time he met his own demon inside his mind? Grimoire's containing demons is even for Julius a reason to be wary.
