The desert should definitely not give more attrition, all the historical forces fielded by Portugal had extremely low attrition rates.
In any event North Africa should be weak. The period rulers knew they were unable to stand alone against the Iberians, so they went out and did diplomacy. Some made their peace with the Iberians for a while others got aid from the Ottomans. For example the single biggest win for the North Africans came after adopting Ottoman tactics and military technology. Likewise, the Barbary Pirates benefited heavily from Ottoman naval technology and logistics.
Historically the average North African campaign went something like: the Iberians siege a city, it falls, there may or may not be one big battle, and the Iberians hold a coastal trade center that ends up being ever less useful as time progresses. Eventually, the Iberians either outright abandon the coastal enclave or they put so little effort into securing (because it is relatively so worthless) that it eventually falls (though the most lucrative remained Iberian for hundreds of years). Pdox very accurately simulates history here. The Iberians can beat the North Africans most of the time (as was historical in the EU era), but they don't really want to beat on the North Africans.
372 AMP is almost a tech or 37 temples (which is 37 gold per year - before modifiers, compared to the pitiful return you get from Fez - once you core, convert, and culture flip it). It is completely not worth the effort unless you have nothing else to do. Of course, historically, if you had nothing else to do, you certainly would take it.