Further development of Internet Radio is on the roadmap. Brian has noted support for OGG/FLAC as being a matter of scheduling the effort.
But Radio Paradise has an individual way of serving up FLAC (see post 31 from Bill Goldsmith of RP on this JRiver Forum thread) that imposes some requirements on the player and creates development issues.
If RP were amenable to providing a usual OGG/FLAC stream in addition to their own API (which serves up metadata and a slideshow) that would put them on the same timing for support of that format in Roon as other stations. But the issues raised by their individual approach is likely to result in delay of RP until a later development stage if the API remains the sole access to a FLAC stream from RP.