The draft curriculum included the following Year 2 elaboration
comparing numbers written with Roman numerals with numbers written using the base 10 place value system and explaining why the place value system is easier to use
As noted by commenter Alex, this elaboration was removed for the approved curriculum. It has been replaced by nothing, unless one counts the Year 3 “Japanese numeral system” twaddle, which was addressed in the previous post. In any case, except for a brief reference in the glossary (Word, idiots), Roman numerals make no appearance in the new curriculum.
It’s somewhat off the point of the post, but there’s a nice one-man Roman history site here, with a good page devoted to roman numerals.