The legths of vehicles in lswr-6-wheel-30ft.dat is 5, but lengths in lswr-30ft-full-brake-6-wheel-elliptical.dat is 6. If 30ft is length, than they should all be of the same simutrans length. It makes the train look funny. Also I think that the elliptical brake vans might need re-rendering, as they indeed look somewhat bigger than the non-elliptical ones. See the screenshot
The correction of the length will need to be done at the same time as the re-rendering: the re-rendering would not just be this brake van, but all the carriages that might realistically connect to it, since they will look incorrect next to the re-rendered van just as much as this looks incorrect next to the re-rendered carriages. For re-rendering to be worthwhile, it needs to be done in large batches: that is not a high priority at present: the plan is to do this at the same time as adding multiple class data.