The mechanic you describe on this page is a compression format made physical. A multiplier stamp is run length encoding, and borrowing an earlier stretch of the note is a back reference, which is roughly how LZ77 works. This is a first impression from the page rather than a full playthrough, so weigh it accordingly, but that framing might be useful for the tutorial. Somebody who has never heard of compression still understands "say it once, then point back at it".
One question about the rules. If a list can be written short in two different ways that come out the same length, does the station accept both, or is it looking for one specific answer? In puzzles built on rewriting, that is usually the moment a player decides the game is being unfair, so it is worth being loud about it either way.