In most cases, using "we" would sound out of place in user documentation (I don't know about unnatural -- why is it unnatural to say "We're ready to begin again?"), but it depends on the audience of your document. I've written user documentation where I used personal pronouns like "we" or "you" simply because the audience required it; otherwise they would have found the language "too formal" and not be as receptive (if at all).
Perhaps in British English, it's "de rigueur" to be so rigid as to not even entertain the possibility of using "we," users' needs be damned, but in the U.S., those of us that write such documentation consider our audience's needs as well, when necessary, in order for the documentation to get the message across be as effective as possible.
That being said, de-personalizing the tone is the default usage for such text, but I'm not convinced in this case that the "on" was used just because it's common (more or less) to do so in French.
The translation workplace 
peer agreement (net): +6