Wonderful plugin. I was looking for something like tis for ages, but still have some suggestions:
1. Make „Update settings“ translatable.
186: <p class="submit"><input class="button-primary" type="submit" name="submit" value="Update settings" /></p>
2. Plugin doesn't work correctly with another plugin: wp-ajax-edit-comments
For example: somebody writes a comment, completes captcha, comment is sent to unapproved list. If person edits that comment using wp-ajax-edit-comments, Akismet sends it to spam list without asking for cpatcha.
Not a big problem, just wanted to tell you that.
3. Can you add a custom captcha possibility? I mean possibility to write your own question instead of captcha. With multiple answer certainly.
Like this plugin: http://wordpress.org/extend/plugins/buddypress-humanity/
4. 215: <...> __('%s spam comments have been automatically discarded by Conditional CAPTCHA
Can you make this sentence in plural form? It is difficult to translate this sentence without plural into my language.
5. And I can share my lithuanian translation:
Greetings, Mantas <mantas.malcius.lt>