no real way to do that, because the tooltips are fixed as the language they're written in =/, possibly excluding strings for built-in parts of warcraft (ie: disease is in wc3 in all languages, maybe each local wc3 pulls up the correct language string for the buff "disease")
nothing custom would translate into the proper language without some BAMF jass
heads up BAMF = badass mofo
maybe just translate it and save each as independent maps.