You were close. There are two tricks here:
  • Your second paragraph must be moved up by one line because a paragraph always starts on a new line.
  • The second paragraph must have the same properties as the first one with the exception of its first indent property, which must be set to the current X position.

  • beginparagraph(0,3,0,'left',0.1598)
      setstyle(&Style1)
      show('Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua. Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat 1')
    endparagraph
    
    @SuperScript('ier')
    
    %% MOVE UP ONE LINE BEFORE THE NEXT PARAGRAPH
    rmoveto(0,-0.16)
    
    %% SET FIRST INDENT TO &current.x
    beginparagraph(0,3,&current.x,'left',0.1598)
      setstyle(&Style1)
      show(' juin 1973 aute irure dolor in reprehenderit in voluptate velit esse cillum dolore eu fugiat nulla pariatur.')
    endparagraph
    
    setstyle(&Style1)
    

Note that you SuperScript function should be simplified since it doesn't require any X,Y parameters:

    function @SuperScript(&sp:string)
      rmoveto(0,-0.06)
      setstyle(&Super)
      show(&sp)
      rmoveto(0,0.06)
    endfunction()
    
_________________________
Technical Product Manager
I don't want to achieve immortality through my work; I want to achieve immortality through not dying - Woody Allen