I recently discovered a ticket booking website https://www.ticket-regional.de/index.php where you can order tickets for various events and excursions.
The site seems to cover Rhineland Palatinate (or Rheinland Pfalz in German) and Luxembourg also, so it covers the Mosel regions and its environs.
The website allows you to search by event date, type, artist, venue or location and if something takes your fancy you can book there and then. There is also a list of booking offices around the region (as well as in France, Luxembourg and Belgium) if you prefer to go in person.
The site has an English option although that just changes the language of the site itself – the search results will also include German events. For music events that won’t usually be a problem, but for musicals, comedy and theatre events it could be more of an issue. A couple of years ago we went to see Starlight Express. Naively we thought that this popular West End musical would be in English, but it was in German. So before booking, do your homework or brush up on your German!