All JBs are compliant with BS7671, if they meet the requirements of BS EN 60670, which is a generic standard for boxes and enclosures.
To be used as a Mainteance Free connection, the Wagos have to be inside an enclosure that meets the requirements of BS 5733, and is marked with MF.
There's no indication that the Line JB is marked with MF.
The BS numbers quoted in the literature, are in fact BS EN numbers.
BS EN 60998 is a generic standard for connecting devices used in domestic installations.
Such devices include screw terminal blocks, Henly blocks and wagos.
The suffix 2-1 refers to screw type, and the suffix 2-2 refers to screwless (Wagos).
BS 5733 refers to enclosures that have cable grips, will retain the connecting device and require the use of a tool in order to access live parts.