Then if that happens just walk away and on to the next. In France agents are legally obliged to present any offer a buyer may make.
If agents in Spain don’t present an offer it’s likely they know the level of mortgage the vendor has so it’s a give away.
Remember their prime concern is their own commission not your welfare.
Is it a great time to buy in Spain right now? In my opinion no.
The market is too much in a state of turmoil and uncertainty. Never buy into a market of any kind until it stabilises relatively and you can leave it at a time of your own choosing. Right now neither of those factors apply.
You may think that’s way too cautious. Perhaps. 😉
However I have been in and out of property markets in Spain and France for years and never once lost money, despite heavy taxation.