"Celtic fans ... , displayed a German flag and indulged in pro-Nazi chants"
in the second image is not a direct transcription from a newspaper article. It has simply been introduced by the writer of a latter day piece who then quotes from the Evening Times.
There was a phase when some stuff I wrote on FF resurfaced elsewhere with certain words altered and I suspect this falls into the same category.
I looked into this at the Mitchell Library 15 or so years ago and found the relevant article in the Evening Times. If someone were really determined they could ask to look through the archives of other papers which are not so readily available. However, I doubt if they would add much.
The nub of the matter is that it is not advisable to make claims without having cast-iron proof in the form of a photo-copy of an article or a reference to it. We've already been round this loop with the 'open secret' quote claimed to have been stated by Billy McNeill at Torbett's first trial. It didn't happen and the use of false references was criminal in academic terms.
In the early days of FF there was a post by someone whose uncle was present at the match and vouched for the bit about 'German songs'. I also spoke to Robert McElroy and his research efforts found similar evidence - but it is all anecdotal.
My hunch is that some Celtic supporters blasted out the German national anthem - how many 'German songs' would they actually know? I have no way of proving this, though, and it is just speculation.