The most scrupulous ones typeset everything to match the fonts they use, I think it depends on the specific page/series you're working with but when I edited sometimes I left them as is, specially if they were badly translated or written (in terms of accuracy). If for instance they appear in the same panel both versions and none of them are in English (for instance, Russian and Japanese) it is better to rewrite everything and replace the Japanese part, but if they're already bilingual I'd probably check the translation is right and if not rewrite them using both versions. In case the English translated song is alone, since they're already using a different font it may be unnecessary, but sometimes both the font and the lettering are so bad that for aesthetics I rewrite them (but in a different font and maybe adding an explanatory note at the end). So my recommendation is however it looks better for you, since in the end you'll be blamed for bad lettering in case they don't like it. Having to redraw or not is also something to be considered, in case it was needed I may leave as is.
