Unless the PGCAC majorly messed up some process or didn't respond in time to inquiries from Spain officials, it looks to me like the system (at least in Spain?) does not work.
As a rule you will not be contacted by the relevant trademark registering office. What happens is that the registration filing is published, and if you are opposed to it going through you will need to file opposition within a certain period after the publication.
That's why organisations with IP to protect typically directly or indirectly (that is via counsel) use trademark watching services. Essentially these scan the where ever the filings are published, and will send you alerts or whatever when something turns up on the radar.
Actually filing opposition is rather tedious and expensive, and particularly when different good/service classes are being used, sometimes difficult to actually be successful with.
What I'm surprised about is that they call it a "registry" when it operates more like a mailing-list, where you should watch for publications and reply when you have objections. A "registered trademark" is more a "trademark advertised on the mailing-list with no objection at the time". Which is not silly, but somewhat inappropriately named.
How else should it be named? A "register" or "registry" basically means nothing more than a big book where stuff is written down -- registered. Then later, you can go to the King's scribe, he'll look in his big ledger, and testify that yes, you came before him and had him register your Marque Of Tradhe back in October 1496, and if the other guy can't point to an older entry in his name, you win.
Having herolds in town squares across the realm announce your entry on the second Market Sunday after it was entered -- i.e, announcing it on a mailing list -- is already going above and beyond mere registration.
This is exactly my point, it is completely different from how the trademark registry works, were people are not expected to know. They can make their claim, and if no challenge happens, they will make it to the registry. They can do this without prejudice and rectifying the situation falls on the previous owner who has to spend significant money to make a case (one they can lose).