I don’t believe there’s any relationship in the colors of the flightpath markers to the marker beacons.
I tested it at KONT Runway 26L (which has an IM IRL and in sim, and has an OM in the sim).
I flew the approach down the flightpath markers, and as you said, there was no appreciable difference in color over the marker beacons while within the path indicators. Interestingly, the landing path markers weren’t even being displayed when I overflew the OM, and they stopped displaying well before I overflew the IM.
I then flew a parallel path to the same runway and again, the markers didn’t look any different, nor were flightpath markers even visible over the OM (they didn’t start displaying until well after the OM) nor the IM (the flightpath markers again ended well before overflying the IM).
The colors may just be showing somewhat brighter because both of the “path indicators” get closer and closer together, and are almost blending together as they get to the end from a distance. I didn’t get a screenshot as I passed the IM, but the path indicators just looked normal.
I think it was certainly a valid question based on how they appear. On a side note, that would have been an interesting feature for them to have added to the sim. Another way of seeing different landing path symbols and reinforcing what they were seeing with the in-plane marker beacons lights and sounds.
Regards