Genealogy / WW2 Polish Prisoners of War [2]

Sorry to start another Thread about polish prisoners of war but no matter what search term I tried I could not find the one I was reading.

My partner had been researching his fathers family history and is trying to make sense of a few things that are puzzling him.

His name was Tadeusz Puk he was born in 1928 in Kolbuszowa Gorna in Galicia and died in the UK. He didn't speak much about his experiences but he did pass on some information later when he was diagnosed with dementia Unfortunately as his dementia progressed he spoke only in Polish and as I am sure was common with many other men trying to make a new life for themselves he never taught his children his native language.

He said that he was taken prisoner by the Germans in 1939 I thought that was very young age 11 but after reading other threads I realise it wasn't. He was moved to different camps and made to work as a builder and road layer for the Germans.
He was shot in the arm and shoulder while trying to escape with other prisoners. They were split up and moved to other camps. He said he ended up in a camp in Northern Italy and was liberated by the Canadians in 1945. He then joined the allied army in Italy. He moved to England after being given a choice of countries where he could move to. From 1946 until 1950 he worked at various Army camps. He then left and moved around England before settling in Rotherham where he married in 1956. He returned to Poland to visit family in the 1960;s

All this he told my partner which is fine however after he died we found a birth certificate which had been issued in 1943 he would have 15 from the Town Hall in Kolbuszowa why and how would he have been able to obtain this given the fact he was supposed to have been in the camps during this time and it amazes me that he managed to hold onto it for al this time. I am more interested in why the certificate was issued than the fact that maybe some of his stories were maybe fabrication although he did have a scar on his arm and shoulder.

We hope to visit Poland as there are still descendants in the Kolbuszowa area.

Any help would be appreciated