I think you are interpreting too much into this.

It is impossible "to maintain a stable one-to-one conversion" in the strict sense only by adjusting the price feed and interest rate.

For example, if one reason for the current difference is the 7 day conversion delay in combination with the steem price downtrend, we'd have to adjust the price toward the expected median in 7 days. That median however is computed from the price feed - meaning you have created a price feedback loop. Which is a very bad idea, since loops have to potential to resonate catastrophically and are not easy to control.

The reasonable thing to do is publish a feed price that matches the market rate. The result will be a long-term stable SBD price that oscillates around USD parity.