Hello.
Spain was not in a good shape after the USA war for Cuba and the Philippines, but they still were a modern country, with a lot of mountains like the one you can find in Morocco, with their old cities built like Moroccan ones, they already had some colonies in Morocco hence had previous knowledge about Morrocan warfare methods. So how did they manage to lose so hard that they needed the French to join in order to anihilate the Rif's resistance ? It's not like the Vietnam for the USA where unknown terrain was fatal, since the terrain was mostly known to both belligerents.
(and also, if you can think of good books on the Rif War from both colonizer and colonized point of view, I'd be very happy)
Have a good day
I did not find answers about everything, but I found this book (in French) speaking a lot about numerous aspects of this conflict (even the political dilemna the USA were having between supporting an anti-colonial spanish guerilla, supporting a guerilla from the first country to officially recognize the USA as an independant country), it's a 1973 historical and sociological symposiumon the Rif War. I found it very interesting
It's readable online here for free and costs like 10 bucks if you want an offline version