Hi DutchHiker, after reading your post I contacted a girl I met in 2012 on the Frances but who walked the Batzan this year and asked her for any info, this is her reply.
"Ok. I'll do my best to finish my account of my adventure. I started in Bayonne and finished in Pamplona. There is some bush bashing. The best and most accurate info you can find is on Eroski Consumer. If you google Eroski Consumer Camino Batzanes you will get good info. Be smarter than me and really explore the website and do take note of the details. Silly me just took the maps and relied on the English guide (1 page only). This website will provide lots of detail. Do book ahead the accommodation particularly the in Bayonne and Ustaritz. The 2nd day, the arrows are sometimes hard to find and sometimes non existent. That is why I would strongly advise you to translate the Spanish guide. I completely missed a village and I got lost. I'll tell you more later."
http://caminodesantiago.consumer.es/los-caminos-de-santiago/baztanes/