For details of the manuscript tradition of Expositiones vocabulorum see Red book of the Exchequer Rolls Ser. iii, 1896 pp1032-1039. A corrupt version of one tradition found its way into early printed abridgments and editions of the statutes. See further Cowley's Bibliography of Abridgments etc (1932) at Ref Bibl Cw UK C875
Some examples of early legal dictionaries are available via links below.
First edition of Stroud's Dictionary (The judicial dictionary of words and phrases judicially interpreted) was published in 1890.
Latin (in a post-classical form) was the usual language of writs and court rolls until 1731 (4 Geo. II, c.26).