have you done aragonés the 'proper' way already? then you will probably remember some stretches, crossroads etc. if not, it usually works if you position yourself as if going the 'proper' way, inspect the signage and continue in the direction of your back.
I have seen very few red-white waymarkes in spain, those that I've seen were fading.
on all my french routes, I don't remember having problems with waymarking. they are descreet but they are there. (except that, when the route follows a road/track for a long time, there are sometimes no waymarks until you have to turn off that road/track.)
I much prefer the GR path going down the spanish side of the pyrenees to the 'new' route with the rusty poles. and also the GR65.3.1 variant after villanúa.