THIS IS NOT A REPEAT of the No. 4 top-voted Revit Idea - submitted in 2016 - asking for the ability to create "Complex Line Types" in the AutoCAD sense of the term.
This Idea suggests that Revit might simply display complex line types correctly in linked DWG backgrounds. Consider it an adjustment to the DWG renderer, not a refactoring of Revit's line object creation tool. This is a case where a word is worth a thousand pixels.
Oh mighty owners of the sacred DWG format, as one of thousands who is often obligated by AHJs, clients, and elusive Standards of Care to represent important objects as lines interspersed with repeating symbols, I beg you, please do this for us.