I actually find it kind of annoying that we use hex strings for a lot of things where they don't add any value. Namely Transaction ID and LSNs. As a result it's always a bit of a pain to ingest these in other tools or do arithmetic on them. Neither is referring to memory or anything where powers of 2 are significant so it really doesn't buy anything in making them easier to interpret either.
I don't see any advantage in converting every place where we refer to timelines into hex and then having to refer to things like timeline 1A. It doesn't seem any more intuitive to someone understanding what's going on than referring to timeline 26. The fact that the *filename* has it encoded in hex is an implementation detail and really gets exposed here because it's giving you the underlying system error that caused the problem. The confusion only arises when the two are juxtaposed. A hint or something just in that case might be enough?
