“However, the building’s boxed-framed architectural style suggests the timbers should have a much later date.”
Building timbers used to be re-used from building to building.
The dendro not matching the architecture is nothing unusual, it happens all the time.
Stone buildings are often even worse. Many are made from recycled monastries.
Ship timbers are often found in buildings, that really messes up the dating.
http://dendro.cornell.edu/reports/report1998.pdf
[snip] A well-preserved juniper post, painted blue and with modern door hinges, was recovered from a modern village house simply because it looked suspiciously old. The sample we were given did not fit anything in our Neolithic inventory, so we sent a piece of it to Heidelberg to see what radiocarbon analysis would reveal. The date is 2117 B.C. +/-110 years, which means it is from some Early Bronze Age occupation near the lake at Kastoria. [/snip]
And, just to complicate things, in some places, ships ballast stones were used as building stones. Thus, one can find stones in one location that came from many miles/kilometers away. Sometimes hundreds or even thousands of miles/kilometers distant.