Yes I found water proofing was pretty poor.
I used sarking on the inside and made sure it extended down the sides. Then had condensation problems, so had to put holes in the top again to vent out the ridge and a hole in the front and back triangular sections.
I then screwed a thin sheet of aluminium to the wooden top completely covering it and extending about 50mm over the sides. The thin aluminium bend easily and conforms to the shape of the wooden roof.
I took the precaution of removing the wooden capping and stamped in a little rounded “tunnel” with a round bar about the size of a pencil along the ridge. This allowed venting at the top.
If you can’t be bothered fiddling about like me ( I just love doing things the hard way) @Rmcpb suggestion above is a good one.