This is a rather old thread – I missed your questions, sorry 'bout that.
The ‘Listen to Roon’ does not do any actual controlling of wither Roon or a specific zone. There’s currently no way of controlling transport controls of a generic Roon Bridge endpoint that I’m aware of.
There are specific endpoints that do have this functionality (and could probably be mapped to Harmony) or that have transport controls that can be tied to a specific remote (I used a Node 2 for a while, with the controls of the Harmony remote mapped to the device – worked great).
These days I use a Meridian endpoint, with the Harmony emulating a Meridian MSR+ remote.