I have added it to the playlist.
Ernste Feier = Serious Celebration
The middle section is entitled "Canon-Fuge", but it is neither a canon nor a fugue... The theme begins like Saint-Saens "Swan". The two voices follow each other in a seventh, but soon another voice joins in the fifth and the canonic texture is abandoned. But it is taken up several times again.
More is to come - but probably not "one Rheinberger per week", as I have to prepare my Easter services...