Hi Clint
Seems I am the only one finding your question interesting. I have been waiting to see if the "big shots" would take a pot shot at this one. Not so, so I make the first round and will see what comes out of it.
I have a book called La Regia Aeronautica 1943-46 by Nino Arena. Can't read it mind you, but I bought it when Italian books were extremely cheap, and maybe I had hopes at the time to learn Italian...hmmm
On page 239 there is a list of an organization called R.U.N.A and what they had at one stage in 1943 (no date given) and in that list there are 2 CANT 26. On page 240 there is a list of what R.U.N.A had on 8.9.1943 and it then says 1 CANT 26 at Ancona. The strange thing is that on page 243 he again list R.U.N.A as having 2 CANT 26. Possibly Luftwaffe requested it but that seems to me just a bureaucratic move. Had they known what it was they probably wouldn't have bothered.....
However with referens to the CANT 18bis there is nothing, which at least suggest to me that in the co-belligerent zone none survived at that stage. Possibly something were in use as a ground instruction airframe, but I cannot verify that.
There is also a slight chance something remained up north but I cannot believe they used it.
Cheers
Stig