There’s really only two solutions. The first is that the template would have to be rewritten to be compatible with the latest templating engine for Connections — in five years I’ve vastly changed it 5 to 6 times, each time maintaining as much as backward compatibility as possible. Connections >= 0.8, some of the oldest backward compatible code was removed in order to move forward. There would be a cost for the dev time to rewrite it which leads me to the second option.
You might be able to downgrade Connections to a version that is compatible with your template. I believe that would be version 0.7.9.7.
There is a third option that I just thought of — you could remove line 54 from the
template.php file found here:
I think the remainder of the template would function just fine.
Oh, there is a fourth option too. Last year, I suggested possibly purchasing the cMap template instead since it is pretty close to you custom template.
I hope that helps!