The reason there are none is because of the drama and mess such a plugin would create. In theory, it seems to be an easy way to alleviate the job of admins with a script that does it for you. However, no plugin can defferentiate a freekiller/immature CT/someone who doesn't know the rules from another CT who didn't break ratio, follows all the rules, and knows how to act respectful.
As soon as the plugin swaps a CT that does not deserved to be swapped because someone broke ratio, the one who is swapped would not be very happy, neither would the T's if a 'fun' warden just so happened to be swapped.
A better solution would be to have more admins that are able to do their job almost around the clock. It has worked flawlessly for our server in keeping ratio and order, moreso than any plugin could.
If you truly want to go with an automated route, you could give this plugin a look:
https://forums.alliedmods.net/showthread.php?p=1966069 I personally never used it.
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