There's definitely more room for discussion on this, but this earlier thread would be a good starting point , with great answers by u/sunagainstgold and u/mrhumphries75.

In my answer in that thread I look at the development of the reconquista concept. The modern usage builds on a medieval concept of a supposed "reconquest" which is highly ideological and was already used at that time in some of the Christian states. However, the specific term "reconquista" was only popularized in Spain in the early/mid 19th century in order to put stronger emphasis on a Christian Iberian identity to be cast as a national founding myth. This trend continued under Franco. So overall a few reasons to be sceptical about the term if not the historical concept.

To quote from the earlier answer I linked to above: For him [Martín Ríos Saloma], the term became only more current in the 1840's while the formerly more common „restauración“ stayed in use at least until the first half of the 19th c. The stronger use of the term reconquista in this way meant a change in focus from the „reestablishment“ of the Spanish monarchy and its institutions to a stronger emphasis on the Christian military campaigns – casting these campaigns as as a national founding myth. For Saloma this change in emphasis was connected to 19th c. developments in Spain like the consolidation of the liberal citizenry and a growing necessity to distinguish historically between Spaniards and other nations, by highlighting the „victory“ over Spanish Muslims. [...] I think that the concept reconquista is nonetheless useful to describe these developments in Medieval Iberia, as described by Castilians like Alfonso X. themselves – while keeping these roots of the term in later nationalist Spanish thought in mind.

Can you specify which historians are skeptical?