The CRW is for less than 1 year because the vehicle you purchased did not have a valid CRW at the time of test. Anybody who is purchasing second hand vehicle should ensure it has a valid CRW at the time of purchase otherwise the vehicle will be overdue its test and receive a CRW for less than a year.
You can find out when a vehicle is due its CVR test by going to www.cvrt.ie and clicking on the “Check my CRW” button.