It is not for the tourist to identify and take legal action. Leave that to the associations as in this article.
However if you want to read more.
Information on Official guides in Galicia can be found here
This is an interesting article, in Spanish about official guides working in Spain. It is a carefully thought out argument. So is the Camino Frances, because of it's world heritage status included in the "
Registro de Bienes de Interés Cultural" and if so does that leave the other route open for unlicensed guides? What law prevails on this?
Thankfully accommodation laws are much clearer.
All accommodation right from camping site to Paradores and that have an official licence to operate will be listed in the Turgalicia website. This only covers Galicia.