the linked Guardian article says:
"The mother said she had been in touch many times with the British consulate in Málaga, but was told diplomatic staff had no influence over the case. “In the end, they recommended I go to the press,” she said.
"A Foreign Office spokeswoman said it was aware of the woman’s case and was looking into it: “We can confirm an incident involving a British national in Málaga on 16 June. We are providing consular assistance at this time.”
It's always true that the British Government has no influence over a case. They can check that the British person is being treated in accordance with the law of the country they are in, and can provide things like lists of English-speaking lawyers and interpreters so the person can have appropriate representation. But they don't pay for stuff; nor provide any form of get-out card from an investigation, if a national of the country concerned would be investigated in the same way.
So I don't think there's any need for petitioning to get her translation services. Aside from the comments above that it's a hospital where care can be offered in English anyhow, it's hard to imagine that FCO haven't provided a suitable list. Don't most travel insurance policies include cover for legal representation?
I spotted that articles are saying that the courts, the police and social services either could not be reached or have refused to comment. Which hints at their involvement, but doesn't actually say so explicitly.