For whatever it’s worth:
The change in dimension of the ornamentation appears to differ from the wood behind. My guess – and it’s really a guess – is that the ornamentations are made out of papier maché. This property of deviating from surrounding wood upon changes in humidity, is apparently used as a means to identify the material.
The attached link directs to a paper that gives some insights on how it is used.
Never seen stucco applied to wood, but perhaps…