Then talk to your troupe. 
Seriously, even when you are the storyguide, it is a good idea to discuss these things with the troupe (unless they are total newcomers to the game). Things like this are rerally minor restrictions or features, and have limited impact on the game.
In this case, RAW seems to indicate that the talisman does not transform by default (otherwise it would be noted in the talisman section on p.98), but a slight departure from RAW is sometimes a good thing to add flavour to your saga.
In the saga I mentioned, most of the player magi are shapeshifters of some sort and power level will be otherwise low, so I felt that this was a concession that would motivate them to create talismans they can easily travel with. This will keep annoyance about having to hide/transport their talisman to a minimum. And what the players have, the opponents will have as well. So if one of their antagonist is a shapechanger, they won't be able to object if he can do this as well. 