I've searched through the FAQ's and rules & guidelines and haven't found anything:

Is it allowed to translate an existing review - let's say from Polish to English and post here? With the correct quotation?

Thanks!

If you're the original author, yes, sure, go ahead. If not, we are on a grey-to-black zone, but I'd still say no. The original author holds the copyright, and it's his freedom and responsibility to submit his works here.

If your intention is to get review on your own band, a better solution is to go to the "request review" thread and send one of the regulars a free promo copy or MP3s, and they'll write one, I'm sure.

In other words, write original stuff, please.

OK cool, thanks a lot for the advice!

I know Napero already answered this, but one has to remember that some people don't post their reviews on sites like MA in order to secure an amount of trafic on their own website. As an example, if you post all your reviews on MA there wouldn't be any real reason for people to visit your own website. Or at least that's how some people feel about it.