Find below some questions I've been asked about this work, and my answers to them.
I would advise you to play the game before reading any further.
No, or at least not intentionally. That which is erased is gone from the game forever, in every respect. It leaves with you.
The game keeps no detailed record or log of how the game's malleable elements have changed, or which players' actions triggered these changes. The only permanent record of a player's passage through the game is in the incrementation of the number found in the bartender's book.
It's possible that one could, through careful study of the raw Selatani access logs, reconstruct players' activities within Barbetween. However, I lack access to these logs. The one person who does have access to them (by dint of running the machine that hosts Seltani) informs me they're not sure how possible it would be, and has no interest in attempting it anyway.
Nope. One per customer. You can keep visiting the Barbetween Age if you'd like, but you won't see the bartender again.
(I suppose you could get around this by creating a new Seltani character and visiting Barbetween with them, if you really wanted to...)
That's D'ni script, one of several nods the game contains to the Myst universe that the Barbetween Age nominally exists within. Their presence is purely atmospheric, and I leave any deeper meaning they might contain as a puzzle for the player to solve, if they wish.