I really miss thoes classic wagons from the german line, they had 1st class, 2nd class and sleepers. It came in blue and red. It's a mistake not to have them there. They were present in TS2019 Ruhr-Seig line before. However after the introduction of TrainTeamBerlin's Payware Mod the sounds and features were raised to advanced level if you still have TS2019 check it out
Red and blue... you're probably referring to the InterCity and InterRegio paint scheme of the 1980's. Not exactly suitable for TSW's modern routes.
It should not an issue because Ruhr-Sieg North is one of the Oldest railways, they are still active today. It's semi-modern. I've seen them in real life there and all over Europe still, a joy to ride in as well
Sure they are still active today, in DB's InterCity fleet. The Ruhr-Sieg-Bahn isn't used by long distance trains however. They could rather use them on MSB.