Hi Riccardo,
I don’t think that (for now) it’s possible that you can have instances inherited attributes from the instancers. In these kinds of situations, it’d be ideal to use ray cast but since the new ray casting node hasn’t yet to be ported into the main build so I guess the other substitutional solution that we can look into is using ‘Geometry Proximity’ perhaps? If I understand you correctly, then you’ll only have to compute the distance of all the points on your curve to the ground-level object (for instance, in this case, it’d be a plane) using ‘Geometry Proximity’, take that distance and minus the half the height of your mesh so that you’d get the real distance of all the bottom points (in the red box position) to the ground-level object and then you can just move those points to the position of the ground-level object.
Not sure if this is exactly what you’re looking for, but here is a demo video.
Screenshot of the nodes.
