Hi Kjetil !
I give a second look to Olve Luft in Norway S.I.G. page:
http://www.luftwaffe.no/ and it seems that the W.Nr list from airplanes in Norway on 10th MAY 1945 (or 10th August both date figured) was done from original German documents from 1945 and so could be consired as complete.
So yes it's ok, those 2 were not in Norway on 10th May 1945!
But this is not enough to convince me that they are not from JG5! They could escaped from Norway few days before trying to join their familly in Germany as others have done? Did this could happen inside JG5 as it had inside JG7 or JV44 for example?