I understand that IRL you'd never use a transformer in this way. But what I'm trying to achieve is not a realistic transformer, more like a voltage-limiter. So what I'm asking is, "COULD this mod be used to make a signal-driven potentiometer?" rather than "WOULD you implement a signal-driven potentiometer?"
You actually CAN use this mod to make a signal-driven potentiometer/volt-limter but it's a complex. Requires a lot of combinators and switches but it can be done. It's not a very accurate potentiometer but it does indeed work.