The WHO's position on alternative medicine seems to be the same as their position on conventional medicine: if it is proven to work and proven to be safe, go ahead and use it.
The document you linked was published in 2013 and outlines the WHO's general strategy and position regarding alternative medicines, though they tend to refer to them as traditional and complementary medicines. Looking at the opening paragraphs on the linked document, you can see their position:
Across the world, traditional medicine (TM) is either the mainstay of health care delivery or serves as a complement to it... TM, of proven quality, safety, and efficacy, contributes to the goal of ensuring that all people have access to care. Many countries now recognize the need to develop a cohesive and integrative approach to health care that allows governments, health care practitioners and, most importantly, those who use health care services, to access T&CM in a safe, respectful, cost-efficient and effective manner.
Clearly, the WHO supports alternative medicine if it is of 'proven quality, safety, and efficacy'. This makes sense, because alternative medicine that works is just medicine. If it meets the same criteria as conventional medicine then it is no different than conventional medicine.
Do note that this is not a blanket statement that all alternative medicines are supported by WHO. Homeopathy, harmonized water, and many other types of 'alternative medicine' are not of proven quality, safety, or (especially) efficacy, so the WHO would definitely not support them.
As a side note, the WHO also has a Spanish version of the document on their site, so it seems unlikely (and unfeasible) that 'some political parties in Spain' are censoring it.