1. A method comprising: in response to a request to identify a supported language to display content by a client application at a client computing device, the supported language having a set of translations for use in translating the content, at least one server computing device making a determination, using a current language tag, that a language referenced by the current language tag is not the supported language, the current language tag comprising one or more subtags, each subtag providing language identification information; in response to making the determination that the language referenced by the current language tag is not the supported language, the at least one server computing device performing elements comprising: accessing a stored set of mappings comprising one or more mappings, each mapping associating a first language tag referencing a first language with a second language tag referencing a second language that differs from the first language; determining whether or not a mapping in the set of mappings includes the current language tag referencing the first language as one of the first and second language tags and a new language tag referencing the second language that differs from the first language as the other of the first and second language tags; using the new language tag as the current language tag, the new language tag identifying the second language that differs from the first language as the supported language; and in response to the request, identifying the supported language to use in translating the content to be displayed by the client application at the client computing device.