I had the same problem. This is not a solution to translate all the fields, but a solution to get that annoying "Submit your review" title out of the way.
Unlike the solution above it will give you the functions of the back end admin area of this plugin.
Actually I went into wp-customer-reviews/wp-customer-reviews-admin.php
If you scroll down to "Review Page Settings" you will have the code for the button and also for the header.
<label for="goto_leave_text">Button text used to show review form: </label><input style="width:250px;" type="text" id="goto_leave_text" name="goto_leave_text" value="'.$this->options['goto_leave_text'].'" />
<small>This button will be shown above the first review.</small>
<br /><br />
<label for="leave_text">Text to be displayed above review form: </label><input style="width:250px;" type="text" id="leave_text" name="leave_text" value="'.$this->options['leave_text'].'" />
<small>This will be shown as a heading immediately above the review form.</small>
<br /><br />
If you haven't noticed, but there the code for the button is defined for the label="goto_leave_text"
For the header it's just the same so if you remove the go_to from the rest of the code defined for the form header and save your file the problem is solved.
Than go back to the plugins admin settings and save your settings as you wish them to be. You can have a different text for the button and another for the form header as the programmers intended to do.
This should solve the review form header from showing "Submit your review"
Also if you're still having problems go to the wp-customer-reviews/wp-customer-reviews.php
And check for this line
<tr><td colspan="2"><div id="wpcr_postcomment">' . $this->options['leave_text'] . '</div></td></tr>
If you checked than you will see that there to many quotes around leave_text remove those so that you have 'leave_text' like the code above.
Save your file and it will show correctly.
For the remaining fields, well you have to translate them manually until developpers put those fields in as well. For multiple translations I recommend you use subdomains, because it will keep languages seperated for reviews and other plugins as well.
I'm sure this will help. Actually my mom helped me solve this :-)