Combine all immobilization types under the same assist category. This way tracking assist and wheeled assist are additive. Destroying an engine should also count for assists the same way as tracking would.
#Immobilization Assist
hard vigil
slate pine
Agreed
gloomy grove
Agreed
hard vigil
Even aside from MoE requirements it would just be nice to get assist for shooting out an engine. Its more crippling than disabling tracks since it increases fire chance and decrease horsepower by 50% even once in the damaged state. On a lot of front engined tanks this can happen pretty often