Proceeds to not be clear about what this means for customers.
I'm not a lawyer, but they're working on it.
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You could turn that around & say that, for the negligible human cost of using a tool to read the messages, your entire system becomes slower.
After all, as soon as you gzip your JSON, it ceases to be human-readable. Now you have to un-gzip it first. Piping a message through a command to read it is not actually such a big deal.
It was either Hepburn, the English title (i.e. rock instead of rokku), or just most sensibly kana/kanji that would have been used for this everywhere, never other romanisation systems, to within a rounding error.
In short, the usual infelicities of Japanese romanization as practiced in the wild on keyboards people actually have, and there is a method to the madness but it's not what any of the standards reflect.