I have to wonder how much that brace bar actually braces if a jumping fish breaks it. Not having that brand of tanks in the US I really couldn't say without a hands on look, but it sounds like it is there to support the light/top more than anything. I've had some good size fish nail the brace bar hard on my tanks, and not even come close to breaking it.
Stainless steel should work fine, I have that on a 72 gallon that was transported improperly, with gravel & a few inches of water. It has a crack, but is not entirely broken, which makes me question yours being a brace bar and probably being more of a support.