I would assume that, at this time of year, it could be difficult to get through from Burketown to Borroloola.
You could try phoning the Roadhouse at Doomadgee to find out if the Nicholson River causeway there is passable.
Other sources of information would be the Burketown Shire Council, who would know if the road west had been graded yet. If not, some of the creek crossing ditches could be a problem. Burketown Police should know if road is officially open or closed - to the border.
For the WA side, try Borroloola Police.
There are significant river crossings of Calvert and Robinson Rivers.
I know there were big floods in Borrolooola a few weeks ago that took out a bridge and cut the township in half.