The post is a bit old, but not too old to not respond.
When using wood I see 2 problems:
1. Blood mites. You always get that with chickens and it can't be avoided. The big problem when using wood is that there are many cracks, holes and gaps in which these mites can hide and it is very difficult or not at all effective to combat them there. Since we live in a hot region, these beasts also reproduce extremely quickly, so that a small, overlooked nest produces a new, large generation in a very short time.
2. Termites. Is eucalyptus termite safe?
The masonry around it makes sense, the question would be whether you should also build a foundation so that no robbers can dig under the wall. I'm thinking in particular of dogs, mongooses,...