Localize terms

I am moving this to the Web Taxonomy module as I do not think that it supports localisation for plugins - or I can't see how. I am not sure how this should be done either. In order for it to work, the autocomplete function and the fetchTerm function should have another parameter $lang which can then be passed to the sparql query to retrieve terms in a specific language. The language of the localised field_data_field_xxx can be passed to these functions.

Having said that, the AAT and other thesauri take years to be translated and they typically focus on one language as their main language of choice (in the case of AAT, this is English). So it is not unreasonable to assume that users would accept the English label of a concept in the absence of a Spanish or Dutch term. In which case there may be an argument for storing the English term in the taxonomy_term_data table and rendering that term in a translated label (with an extra sparql request) when the record is viewed.

Correct - multilingual infrastructure would be required in web_taxonomy, for individual plugins to build on it.

I think that this is a valid requirement. For STW Thesaurus for Economics / Economics Taxonomies there is already an issue for that: #1461064: Add multilingual support). Guys at FAO have sucessfully added multilingual support in Agrovocfield. And the Eurovoc people surely would deny any assumption that there is something like a main language ;)

Unfortunately, this feature requires considerable work, so I'm not sure when I get at it.