@voxuer1 That means the thing on the left side of the dot doesn't have a function with that name. You probably need to get the reference to your module in a different way.

@voxuer1 working code

const var Speed = Content.getComponent("Speed");
const var SpeedValue = Content.getComponent("SpeedValue");

inline function onSpeedControl(component, value)
{
local formattedValue = Engine.doubleToString(value, 2);
SpeedValue.set("text", formattedValue);
Console.print("Slider Value: " + formattedValue);
};

Content.getComponent("Speed").setControlCallback(onSpeedControl);