L4H to my knowledge there is no connection between crf & issues with bone. Some cats and dogs don't do so well on certain meats and some need lower bone amounts. Older cats also don't need as much bone as younger ones, of course gaugeing by the condition of their poop is an easy way to spot any issues.
In Duffy's case it is likely the very small spots the radiologist noted on her intestines that is being irritated by the bone, like a very mild case of IBD - he wasn't told she is rawfed, but this was a possible cause of the recent issues she was having pooping, that was suggested by my vet. He should call me in the next few days to go over the radiologists findings.
Avoid biting when a simple growl will do
The Spirit Lives As Long As Someone Who Lives Remembers You - Navaho Saying
Vindication ~ For all those pets who became sick or lost their lives from tainted pet food