Ah. It was the "Unable to set a control input in the software radio" part that threw me. I thought you were reporting a bug where you couldn't change those values, or the changes weren't taking effect.
I remain confused about your confusion, then. The text in parentheses is the control trigger, as you put it, for the given software radio input channel. And what that value is depends on the channel mapping in the currently active radio profile.
So if you're using the InterLink radio profile, for example, it's a straight-across mapping: channel 1 from the controller maps to RealFlight input channel 1, channel 2 from the controller maps to RealFlight input channel 2, etc.
Contrast that with the Spektrum radio profile, where controller channel 1 maps to RealFlight input channel 3, controller channel 2 maps to RealFlight input channel 1, etc. In this case, the dropdown in the software radio will look like this:
Input Channel 1 (Channel 2)
Input Channel 2 (Channel 3)
Input Channel 3 (Channel 1)
Input Channel 4 (Channel 4)
...
If you're using the InterLink, the controller channel values are the same as ever, and are labeled on your controller.
Does that help? For any other controller we have no way of knowing what's driving a given channel. Maybe you're saying you'd like it if, when using the InterLink, the old labels still appeared?