NOTE:

We think that the correct way to configure falling back to other languages
is setting your LANGUAGE variable to your preferred list of locales
in the file ~/.bashrc. 

We don't know how to tell gnome or kde how to do this, and we may be 
wrong about the method described.

Someone in Nicaragua that speaks Spanish and English might use:

export LANGUAGE=es_NI:es_ES:en_US

Someone in Argentina who speaks Spanish and Portuguese and English might use:

export LANGUAGE=es_AR:pt_PT:es_ES:en_US

If you set your LANGUAGE variable, you can start ardour2 without changing
the LANG variable, assuming LANG is set to your primary locale in the first
place.

Other programs may also follow this translation order. This may not be 
what you want.

A more useful LANGUAGE setting would fall back in order through all the 
most similar dialects but we leave creating that as an exercise for 
the pedant.