In my experience with walking in active fire areas, on my 2005 mainly through the South of France, I'd say that basic precautions if you're close enough to smell smoke (the smell can travel quite far), sleep in places with multiple exit routes, and if you can't walk through an actual fire area from risk or a Police barricade, walk around it, and downwind, that is to say where the wind is blowing towards the fire not from its direction.
Otherwise, conditions during the heatwaves this year in Spain and Portugal have mainly forced heat management stuff, and well, active fire zones are typically not that large in comparison to the length of a Camino, though clearly there can be exceptions. I've not come closer than about 50K to any active fire on this Camino.
It will obviously be more difficult where a Camino passes through a semi-wilderness fire area, as plan B options avoiding the risk might be thin on the ground.