In Empire Strikes Back, we see a transcription of what R2's beeps and bloops mean, but it's not English (sorry for the low quality, it's from the 2004 DVDs):
I'd assume it's what Basic looks like when written, but is there some point in the the Star Wars films we see written English instead?
(This sort of spun off from a discussion in How do people understand astromech droids?.)