The author of that last report was in hospital in Marston Green, Birmingham. I was born in the same hospital some years later. Small world ....
The use of the PIAT at high angles and against structures is mentioned in a book I have (Anti-Tank Weapons, by Terry Gander). An effective range of 350 yards is quoted, which agrees the reports here. The PIAT apparently had a bubble sight to allow the desired angle of elevation to be set - apologies if this is common knowledge.
Bryn