Whether it was actually terrorism or "just" sabotage depends on what they were trying to achieve with these iron rods (glued to track). Derailing a dozen passenger trains at 150 km/h would instill fear at minimum, and probably results in deaths.
But merely sabotaging the signals to turn red, assuming there's no risk of that not working and trains getting derailed anyway, wouldn't meet that bar, at least imo.
Ultimately it's the difference between 2 vs 3 days of community service with the usual judges here... (only if you're a Russian privacy software dev, do you get actual prison time).