Scheper seems to indicate that it is the addressing system alone which provides the "personality" of a zettelkasten, whereby he's actively providing personification of a paper and pencil system by way of literacy. We need to look more closely, however at the idea of what communication truly is to discern this. A person might be able to read an individual card and have a conversation with just it, but this conversation will be wholly one sided, and stops at the level of that single card. We also need the links between that individual card and multiple others to fill in the rest of the resulting potential conversation. Or we will rely on the reader of the card extending the idea or linking it to others of their ideas (and that of the zettelkasten), to grow the system and thereby its "personality".
Thus the personality is part that of the collection of cards using their addresses and the links between them. This personality, however, isn't immediate. It might grow over time reaching some upper limit at the length of time of the user's life, but much of its personality is contingent upon the knowledge of the missing context of the system that is contained in or by its creator. Few zettelkasten will be so well composed as to provide full context. (cross reference: https://hyp.is/5gWedOs7Eeyrg2cTFW4iCg/niklas-luhmann-archiv.de/bestand/Zettelkasten/zettel/ZK_2_NB_9-8_V).
The question we might want to look at: Is there a limiting upper bound (a la a Shannon Limit) to the amount of information that a zettelkasten might contain or transmit, even beyond the life of an initial creator? Could it converse with itself without the assistance of an outside actor of some sort? What pieces are missing that might help us to define communication or even life itself?