I think most kinds of wood can be used in Hugel beds. If the wood inhibits growth in other plants I believe that it's best to let the wood rot for a little before using it in beds.
"A society grows great when old men plant trees whose shade they know they shall never sit in."
olive wood is one of highest quality woods, its used for fancy furniture, flooor making and tool handles. if you have a lot of good olive wood mabe better idea is to sell it or use it for carpentry, and make raised beds with something else
Last year, this tiny ad took me on vacation to Canada
It's a bit like "run away to the circus" but with gardening