I wonder if it’s possible to send MIDI messages from a H9 to a MIDI device that is selected from “connect MIDI device to Eventide device” section of H9 control software, or is it a one-way connection.
I’m trying to avoid getting one of those USB host devices and use a tablet lying around to make H9 work as a controller for another Fx pedal which doesn’t have DIN MIDI but have an USB input
I don't think it can work that way. I think it would be much easier to use a MIDI-USB cable/converter to do what you want to do.