The refund window (time) is quite short on the Play Store. Just hours I believe, though I haven't checked. That is controlled by Google, and JRiver can't provide refunds outside of that time.
The Play Store description says that JRiver for Android can work as a DLNA or UPnP Renderer, and it can, I think. I can push audio files from a MC Server installation to JRiver for Android, using MC as the Controller. But I can't tell if that is using UPnP/DLNA or JRiver Media Network. Not without running Wireshark and checking what is being sent between devices.
I can even connect JRemote2 to a MC Server and use JRemote2 as a Controller to output audio to JRiver for Android, which is seen as a Zone in JRemote2. I can then close JRemote2 once I have told it to play tracks, and JRiver for Android continues to play the tracks.
Device Spy, which analyses DLNA devices on a network, does show JRiver for Android as three devices. A UPnP/DLNA Renderer, a DLNA Server, and as a JRiver Library Server.
So Im really not sure if JRiver for Android will meet your needs, as you are specifically using UPnP/DLNA servers, and not JRiver Media Network (Library) servers. The full version of JRiver Media Center can certainly see DLNA Servers, but I don't know when or if JRiver for Android will see them. My DLNA Servers are all MC DLNA Servers, so I can't test third party DLNA Servers.
Maybe JRiver can clarify if DLNA Servers are supposed to show up in JRiver for Android. Or you could search the forum for information on that, perhaps in announcements of JRiver for Android.
Note: Any DLNA Renderers such as VLC, BubbleUPnP and lots of others, should see your DLNA Servers. So the JRiver for Android DLNA Renderer should see them theoretically. Maybe that is an oversight by JRiver, or just a timing thing.