Minna says in the comments that it can be either, but those markings cannot be from the original attack (that was me). The whole train is different, and while I suppose they could have made extremely extensive changes in the train, as in it theoretically still being the ”same train”, modifications include a complete overhaul of the structure of the carriage. Not to mention the fact that the walls appear to be made of entirely different material (sheet metal vs heavy plate). So, the section that was scratched, would have been completely rebuilt. Using the same meta would include reworkimg it to the smelter, or at least almost so. Hence any marks would have been gone after the reworking.
Now, I’m not 100 % sure it is actually the Dalahästen Lalli is inspecting, but since all the other trains are under covers it very much looks like it is. Also it seems unlikely they would save than one train, as several redesigns have taken place between the accident and this date (admittedly we don’t know if all or even any of the designs were ever built).
And finallly, the KRRONNKKS during the journey clearly indicate that there likely are marks to the train every now and then even when there isn’t a breach.
Btw the decisive action all train guards are taking clearly indicates they are not blindly trusting the train’s structural defenses (any more) and while breachs probably are rare, they are by no means unheard of.