Are you a "pro" or is this a DIY project. Pro level remotes are usually associated with restricted access programming tools. In this respect URC is a bit "leaky".
family of remotes might offer something for you, but I don't know if any of these have an RF option.
I'm not sure what you mean by: 'but the Hub is not able to tell "keypresses" of the remote controller.' If OpenHab can translate commands, then the codes, IR or IP, associated with a remote key are arbitrary. In this context the most significant issue would be having the remote indicate which activity is the current activity. Otherwise, if you simply pick up the remote, you don't know what it is controlling.
Full disclosure: I'm a pro and I ignore Harmony because I can't customize as much as I want, but it seems relatively capable. Even in the pro world, it is hard to associate arbitrary strings with a key. In an effort to offer "quick and easy" programming, one picks a target device, "activity" if you like, and the keys are preprogrammed with appropriate IP or IR codes. Some additional customization is available if one subscribes to a "driver" kit from the remote manufacturer, but access to the driver kit is even more restricted.
Maybe I'm misinterpreting your project. I'm assuming that you can route IR signal levels to OpenHab, and these will be transformed into a character string that OpenHab can recognize and translate into commands for your devices. This is why I claim that the codes emitted by the physical remote are arbitrary.