Might wanna look into it a bit more (though I have no idea where to start), the Romanians numbered theres the same way for the most part, but they were still broken down into units, so I'd have to assume that the Spanish probably did the same thing.
The 109G2 "White 7" for example was both the 7th 109G2 received by the ARR and assigned to Grupul 7 Vanatoare (strictly coincidence).
I have to take your word for how they numbered theirs as I know nothing about the Spanish AIr Force, but looking at how many contemporary nations numbered their aircraft reseived from the Germans, my first assumption in looking at it was that it was the 135th 109F and was assigned to the 6th squardon, or something to that effect.