Did you try other RK24 models to know if this is a characteristic of the loader valve they use or maybe a problem with your machine? Normally there isn't any adjustment in the open/close behavior of the valves since the action happens as machined spools move through machined galleys in the valve body, and the shape of the spools/galleys is what gives the valve feel and precision.
Sometimes you can add a restrictor or needle valve downstream to modulate the effect but it will also reduce the overall flow rate.
99% of it has to do with how good the valve is. There are big differences in this across tractor brands and models, so I feel like it's super important to try this out when shopping tractors. I have been on tractors that offered very precise feathered control through the loader valves, and others that feel like on/off switches.