I remember asking the same thing when I got mine, so it's NOT a "silly question...."
Your privately owned "non-CR" guns do NOT have to be logged...just like any "non-CR" guns you buy AFTER you get it....the CR gives you no advantage over any non licensee when buying non-CR guns, (except maybe quicker NICS!
You technically have to log only guns bought "via" the CR.....
However, the "gray areas" are any CR qualified guns you owned PRIOR to getting the CRFFL (probably not) as well as any CR guns you bought via 4473, like at a retail store that didn't take your FFL because they didn't understand it....like the few I bought at Dunham's....(PROBABLY!)
But the issue might be if you SELL them....you'd have to follow the rules to sell them just like any of your other CRs....
The way I figure it, why take the chance? Log them, just put down on the log "via 4473," or "previously owned...."