https://forum.atlas-games.com/t/spell-effect-to-allow-casting-underwater/7390/19
Probably need to continue this here.
I don't object to the spell, per se. I object from two people being able to learn Hermetic Arts from the same source at the same time. At the very, very least, it needs to subtract from the SQ, much like a teacher does when multiple people are taught by a teacher, except a teacher cannot teach multiple people Hermetic Arts.
If the spell/device is going to be in use here, I think it should be flavor, as in someone is studying from the book, without anyone else knowing what he's studying. Things then fall apart when someone tries reading that book physically while another is reading it via the spell/device.