I'm talking about lyrics supplied by plugins. While continuously listening to a URL, the metadata changing event of the stream can be taken as a reference for track starting time, then it may be possible to show synced lyrics for streams too. Also the supplied lyrics for the previous track can be cleared and send the lyrics request broadcast for the new track(ACTION_NEED_LYRICS).
I'm not sure about the reliability of this method, may be buffering, or audio processing delay could affect the reference time point and may spoil the syncing.
here is a link I tested: https://stream-156.zeno.fm/agtp9c146qzuv