Numbers are little low. Looks like your procedure is correct. A lot of people make mistake of not having throttle WOT. Yes, cold engine typically does not seal as well, but is usually down only -20-25%. Here’s additional test data you can get:
2. Repeat test with warmed up engine
3. Repeat with warmed up engine with ~1cc engine-oil squirted into cylinders through spark-plug hole.
These numbers combined with your original test will help narrow down areas to inspect more closely. Might want to check cam-chain tension and cam-timing.