Two weeks ago I led a private group of roughly 10 on this route:
Cleared Ridge -> Mt Barney Retreat (permission obtained) -> Mowburra Peak -> Durumlee Peak -> Cedar Pass (bypass Focal) -> Montserrat Lookout. I walked the same route three years ago. The landscape has significantly changed.
The ascent of Mowburra Peak three years ago was mostly on well defined 4WD tracks used by the retreat for 4WD camping. They are heavily overgrown now, and some are difficult to even see. However the ascent was straightforward and not difficult. Some parts of the rainforest that merges in from the left near the peak has been burned back by the bushfires a few years ago, although it is still there, just the boundary has receded.
We trekked across to Durumlee Peak as well, the rainforest was unhelpful here, being quite resistant to our efforts to reach it, and there was a dense thicket blocking approach at one point we had to significantly detour to get around, but we finally did make it. Not much of a view here, we trekked a little further north to a mossy rocky outlook, but the views were far better on Mowburra Peak. Maybe we missed a much better viewpoint here.
The descent through Cedar Pass was the same - rainforest, but not so dense as to be impassable. Vague signs of a track were encountered many times, but it always seemed to fade out. Where it existed, progress was fairly fast. I seem to remember significant wait-a-while here three years ago, and we encountered much of what looked like it, but did not snag or have barbs for some reason, just buds. A seasonal thing, or misidentification perhaps? We never got snagged by wait-a-while in this section. Some gympie gympie was encountered, and we trekked further south of Focal Peak than I did last time. This did mean we encountered a few challenging gullies to cross, in one case shuffling across a large fallen gympie stinger tree, being careful not to touch any of the leaves. This was surprisingly easier to move through than I remember last time. There was water here in some of the gullies, mostly soaks but a few water sources of an inch or two deep. Enough to fill up if you treated it.
The ascent out of Cedar pass onto the ridge between Focal and Montserrat - steep, but not particularly troublesome, the vegetation did not pose much of an issue, fairly open eucalypt forest.
Once we got onto the ridge between Focal and Montserrat, the real trouble started. It was clear the fires had been through here. It was intensely overgrown, with many, many fallen trees and debris - densely so. All of the vegetation was thick and resistant, and an awful vine covered almost everything, constantly tripping, tangling and hampering efforts. Progress slowed to a crawl - it took forever to reach Montserrat from here. It never really cleared up until within 50m or so of the peak. I do not remember this section being difficult at all last time, even remembered a faint footpad here. There is barely any trace of it now. The approach to Montserrat is greatly hampered. This was easily the worst part of the entire journey.
Once Montserrat Lookout was reached, the war was won, and it was an easy walk down the usual way, and back to Cleared Ridge.