Hi Isaac,
Thanks for the concern - much appreciated.
I have been honeycombing like this since the mid 1980's.
Everything has to be right ; foam quality/work, wood grain orientation, bonding of wood to foam and stress focal points must be avoided/managed.
With a diamond pattern there is sheer web at all chord depths by the full length of the panel so if the foam and the bonding is good such a failure will not happen - unless there is some stress focusing.
Also I am creating a composite skin.
I believe it will be ok.
Thanks again.

Brian