Thinking of getting it, just some Questions first.
What is Interstitial Portrait/Landscape Mode? Is this the first or second edition of Interstitial?
portrait and landscape are single page or double page! This is first edition!
Are you planing to get Interstitial on to a VTT like Foundry?
it would definitely be cool! I unfortunately have looked into it and the level of coding required eludes me. But maybe one day!