I don't know when DTG introduced the change, but suddenly, for the first time, custom CC liveries are appearing on German passenger coaches That's one of my Silberlinge, not the somewhat later Mittenwaldbahn coach with blue rails and markings (and, admittedly, a period correct interior)
They introduced this feature a while back........ It's called "AI Livery Usage". And no, it is not limited to AI because I got one of my liveries for the coaches in some 193 FLX Vectron Services. But having a Coach/Locomotive livery show up, is based on RNG.
I've noticed custom passenger cars showing up from the release of San Bernadino Line. Custom rotem coach cars and probably bombardier bi-level cars will appear in AI and player trains at random. However, prior to SBL I have never seen custom liveried rolling stock appear in trains, and I've searched in both Cajon Pass and AVL. Anyone have any experience of custom cars appearing in Linke Rheinstrecke?