Any decent person would take that risk, for their mother's health.
At least in the US, there's a fairly large industry built around mold testing & remediation. Laboratories need to be inspected & certified, and you can do your own home air testing and receive the results directly from the lab.
Compared to a family member's health, testing is very cheap.
Vs. if you're testing to make sure the house isn't rotting - that's trickier. Many sorts of mold can be underachievers at releasing spores (which is what the common air tests look for). Or the spores could be released in a wall cavity or something, where air doesn't circulate and carry them to where you're taking samples.
I've no idea what the situation is in Spain.
Changing topic - my mother's mental health & vision were destroyed by an undiagnosed case of https://en.wikipedia.org/wiki/Giant_cell_arteritis . America's health care system burned through incredible amounts of money for fancy high-tech scans and tests. It did not bother with having a competent doctor sit down, and really think about what might be causing mom's slowly-worsening symptoms. That would not have been hard - mom was in the very highest-risk demographic for that disease. And after it was too late - my optician was able to diagnose her in seconds, sight unseen, from just my in-passing mention of her eye-related symptoms.
(Yes, I also got the clear feeling that the health care system did not care at all about an elderly woman's declining health);