I agree. Best not to spook him with talk of the future/time travel.
It sounds like they already have the Cosmos key, finishing Fragment 12 and the Assessment. It sounds like they're stuck on Fragment 13 - we could ask him to forward us/copy&paste the Book's Fragment 13 email and see what clues they already have to help them crack it and get the fragment.
As for small talk, we should make our lodge impractical for him to travel to - with all the danger swirling around him from the Silver Storm, he may want to meet in person, which we cannot do. I think telling him our Lodge is in Great Britain would make sense, especially with the timing of the 4 pm/4 am timing of our exchanges. It's not that big of stretch.