Is it possible to map a button of a remote control to some unique custom event that EventGhost could handle? I mean an event that will not coincide with other (standard) system events, e.g., it will not be treated as a keyboard key-press or a multimedia control event as it is now.

I've made a tutorial how to do this quite a long time ago:

It should still work, but I've stopped using Windows so I can't confirm it.

I don't know if Generic HID plugin has seen any changes since 2014, so you can first try the one provided in the default install and if it doesn't work properly (no key hold detection) you can try mine, which I've linked in the thread. But keep in mind that this is a modification of Generic HID plugin from 2014 version of EventGhost so I don't know if it's still compatible or not.

It still works, thanks!