Using the external ai will disable the deck rules inside hearthranger, and I believe the default rules for silverfish are control anyway..

But as JoyAdmin has posted many time silverfish ai is still newly implemented and it is not under his control how it works with hearthranger,

If it isn't working to your likings I would suggest just using the inbuilt hearhranger ai and creating your own deck rules, or using the standard default until you are able to create your own.

thanks