increase its speed, it moves like a heavy tank which is pretty stupid cuz its using the medium tank chassis with a even lighter turret.
Relic designed every unit with one historically acurate feature in mind that defines the unit, then they think of other stats to make it more or less ballance. In this case this one defining feature is speed as centaurs were basically comets with underwhelming crusarder engine. Crusarder is way lighter tank you know and the engine was the same.
Also if you dont like even such a basic historical argument then lets say it would be just a boring ostwind copypasta without any special feature if you just buff the speed. Basically this is that one little thing that cannot be changed, move on to other ideas to improve the unit.