I believe you said the older one was readable with tuner and it has r14 host? It doesn't matter how old the radio is, what matters is the host inside it.
If it has R14 host, you must use R14 or greater CPS. Whenever a major Host update is done, Motorola releases new CPS.
You cannot use an older version of CPS on newer firmware. It will not understand any newer features and most likely, it will not understand any codeplug structure changes.
You must either upgrade your CPS as your error message states or rollback the codeplug version which probably isn't going to happen.
Your best bet is to purchase the latest CPS from Motorola.