When you trigger a parameter on the H90 such as active/bypass or an algorithm specific performance parameter, there will be a popup indicator to show you have triggered this function.

If you are in Perform Mode, you can see the states of whatever performance parameters you have mapped. Sorry, I don’t think its possible to have additional feedback for the external aux switch states.

If you need more feedback, I would suggest a different aux switch with LED indicators, or you can use a MIDI controller with a display that can give all sorts of feedback for the states of the controls.