Im 95% sure this relates to Europe, California, and to some extent Australia, where there are strict rules related to modified cars.
Some European countries require 3rd party documentation from independent testing facilities in order to approve modifications, like here in Norway, where we use the German TUV.

 

Nothing about a shock would preclude it's use in most places - other than ride height adjustment is technically illegal here - and only really an issue on initial compliance.......or if you tend to draw negative attention to yourself, ie being a d!ck, in public. The JDM only, would be generic boilerplate to avoid having to deal with whinging foreigners if they buy something rhd, that won't work on lhd.

Looks like autoexe sells an overhaul kit, if that way inclined. No doubt they're made for them by another company anyhow.

As to settling, probably more due to installation on a 2 post hoist or on stands and tightening pivots at full droop, rather than anything about hydraulics "settling in". Wouldn't expect there's any compliant rubber in spring seats on the ohlins either.