It's a learning opportunity, for Hermione. For all that she has put forward the research project, and lead on it here and there, the cryptography component is one she has little knowledge of - here, at least. As long as her magic is limited, she can't make her Protean charmed coins, so the neat tricks she's picked up in her life are just concepts.

Petra is an interesting mage to learn under, so she is nearby as soon as she begins to work on the symbols.

"Oh, of course, my pleasure." At this point, lumos is a spell Hermione can perform without the vocal command, without having to channel her magic. (Domestic spellwork, she'd be inclined to think back in her world, with a little lips-pursing of disappointment.)

The tip of her wand lights up, shedding bright light in an area around it, and Hermione aims it where it would be more useful.

"How is that?"