Oh, I see what you're saying. Yes, the left interior would be visible alongside the inner flap.
I'm not convinced that's the natural order in which people will read things, but yes, they're both visible at the same time. I think even though left-to-right is the normal reading order, my instinct as I'm opening something is to read the flaps first, then the interior. I designed mine so that the timeline is on the interior left panel, knowing that it would be visible alongside the inner flap, but still expecting the inner flap to be the second thing people read.
This may vary from person to person though. It's clear from Graham's post on trifolds that he's also a "flap first" guy because his numbering goes 261 345. But I'm sure you're not the only one who has the opposite instinct. https://lordgt.itch.io/children-of-eden/devlog/925521/writing-a-tri-fold-a-look-...