Hi,
Yes, having a spline-to-surface projection for spline scattering will be the ultimate solution. But as array modified in Max got improvement specifically in spline scattering, the same branch in Chaos Scatter got lower priority.
For now, you can either use the Array modifier itself for spline scattering and projecting the spline to surface.
Or use conform modifier for the spline, making sure it is normalized/devided into enough segments - and then using it with Chaos Scatter.