Okay he feels like he almost got that word 'signage-already-optimized-do-not-attempt-further-optimization-mark'. Especially given the context, it sounds like it should be a cognate or descendant of 'naively-looks-subject-to-a-further-optimization-but-is-not+mark', that society puts on physical objects that look broken or improvable but which are actually that way for Nonobvious Reasons--
Ohhhhh maybe he is from the past version of dath ilan! And that's why Baseline has new words and she expects him to be smarter! He would not be trying to explain the nature of a completely unknown world to a new arrival by recounting only his own personal experiences, he'd lead with the clearest or most enlightening examples that had happened to other people. But if she expects him to have much lower sample complexity / higher general intelligence, then she is probably expecting him to do well enough about inferring everything she means to communicate using only data she has personally witnessed. Probably all of society converges more to norms of 'when possible, answer only using data you personally have verified directly' as it becomes possible to deduce more from that and there is less need to hear about other people's data.
(Othrem does not immediately conclude that this new hypothesis is correct, because he is not seven years old (as is the age you start to be trained out of that sort of thing, by the gauntlets of lures and gotchas that children run into when they get old enough to start seriously trying to escape their children's-escape-bedrooms).)