Could it be a combination of roman and ”arabic” numericals so that it stands for Regiment X (i.e. 10), and then company number 2?
Interesting article. I did not know so many German troops served in the American War of Independence. Interesting that the Jägers lack of bayonets was perceived as a weakness. The text mentions they were armed with hirschfängers and not hangers. Did you check out this website mentioned in the bibliography: “Edged weapons of the Hesse-Kassel Jäger Korps,” http://www.jaegerkorps.org/
, accessed Dec. 9, 2014.?