Having the ability to set custom attributes on curves generated by HDAs in Unreal, opens a lot possibilities when driving Houdini setups from Unreal.
Apparently, right now, there's no way to do this. The only generated attributes are v@scale and p@rot. And while v@scale can be hijacked for other purposes, p@rot is not as useful for that purpose because of the euler->quaternion conversion.
Maybe there's a way SideFX can offer a workflow for "Curve Input" op, by generating multiparms per asset (Detail attribute), per Curve(Primitive attribute) and per Point(Point attribute) where the artist is allowed to dial in custom float, integer, string, etc values.
My clip doesn't show this functionality but the idea would be to have the amount of prims and points being synced with the existing geometry automatically as the curves and the points are created/deleted.