Just to follow up - I was able to check these in person yesterday and can confirm that 1018-4 and 1018-5 have no signage at either end. LA 1018-3 is signed at both ends. I also drove LA 124 to its end and found that it is now paved and signed to
this intersection with LA 3102, instead of ending at the east intersection with LA 3102 as it currently is in TM. You can see in the GMSV imagery that it was under construction a few years ago. It is fully signed to that intersection now, so can be extended in TM.
Regarding the question about the route of LA 124 through Harrisonburg (in your link above), it is correctly routed in TM according to its signage.