I think it would - it might require some dedicated tag wranglers but it would present the user both with a standardised system (start writing 'eng' and 'English' is suggested) and the option to add new languages that aren't in the system (that could then be wrangled).

The AO3 system also connects all versions of the same tag; you could write 'English' of 'anglais' and both would link to the same thing. This might be a bit of work, but as there are a limited number of languages (and spelling mistakes etc) the workload should increase pretty quickly after the first manic implementation.