I have seen a lot of Spanish and Italian percussion/flintlock pistols, and I don't know how anyone can say that's a copy/modern reproduction from the pictures.
The buttcap is a distinctive style of the French and British makers of the late 18th and 19th centuries. The cap is scalloped and forms a deep ridge that was considered (at the time) useful for clubbing a man's skull after the pistol was fired. The buttcap would fracture and open the skull. Copies of this distinctive design are almost always more shallow and show that the original purpose is unknown to the person copying this feature.
The butt and fore-end furrules are also well done and not typical of modern reproductions. Obviously any skilled gunsmith could produce something like this if they wanted to spend the time, but then the pistol has value for those skills alone.
Finally, the back-action lock isn't something I see on the low cost Spanish reproductions (or for that matter, that I've ever seen on modern Spanish reproductions).
In the 19th century there were some very talented gunsmiths in both Italy and Spain, and the damascened pistols from Spain are their own special niche of collecting (and one that I don't have the money to pursue). However, that's not the style of the Spanish pistols of that period, and the decorative flourishes aren't typical either.
I still maintain it's either a French or British set from the mid-1800's (more likely French) or the work from a talented smith's shop who in no way was trying to produce a "fake".
Disassembly will answer most of these questions.