[Correction of your English follows. Feel free to ignore this as nitpicking if it is not useful to you]

Russian "мы с [кем-либо]" is properly rendered in English as "[Someone] and I", so here it should be "A group of fellow aspiring rationalists and I..."

A currently-ongoing activity is typically rendered using the present continuous tense (-ing), and here it should be "...are working on..." ("work on" suggests that this is your job, which you do on a regular basis, rather than an ongoing activity done once.)

Because this need not be the only such translation, and it has not been specified previously, you want to use the indefinite article (a/an): "...a Russian translation of Lesswrong."

"The project is considerable" -- I'm actually not certain what was meant here, but based on the next clause I suspect you mean, "The project is fairly extensive".

Finally, one more issue with articles. While there could be many translations, only one site could be named lesswrong.ru, so here you don't want an article at all. It should read, "Would it be imprudent of us to store our translations at lesswrong.ru?"

Editing to add: I just realized I misread "impudent" as "imprudent". Regardless of what anybody here suggests is the most prudent choice, it's certainly not impudent.