There were not. I checked steam on both tsw2 and tsw3 and the only thing is the one where you complete all scenarios but that's about it
The G6 had no Achievements in TSW2. The last few Loco DLC didn't get any achievements in TSW2. But what surprised me was that in TSW2 the Class 313 didn't get any Achievements, but in TSW3 the DLC has 3 Achievements. The Question arises why the Class 313 now has Achievements but the G6 does not. I guess it's because the G6 is a 3rd Party Product and not from DTG.