Yes, such placement files will be widely available, from almost any other EDA flow, which is why I was looking for a means to apply that info.
Digging about in your examples, and using the references here & some google, my learner Python comes to be this
import sys
from pcbnew import *
pcb = GetBoard() # Read loaded PCB design
RefNm = ['U1','U2','J1','J2'] # Lists of Ref X Y R M to apply to just imported netlist/coarse placement.
RefX = [7050.0,7050.0,6400.0,6400.0]
RefY = [4700.0,4100.0,4100.0,5250.0]
RefOri = [0,45,90,135,180]
RefSide = [False,True,False,True] # Flipped is True for Bottom
# Scan the lists test - Requires lists of RefNm, RefX, RefY (mils), RefOri, RefSide, & scans to apply those to the parts.
for Idx,Rn in enumerate(RefNm):
print "# RefNm:",Rn," ",RefX[Idx]," ",RefY[Idx]," ",RefOri[Idx]," ",RefSide[Idx]
nPart = pcb.FindModuleByReference(Rn)
nPart.SetPosition(wxPoint(FromMils(RefX[Idx]), FromMils(RefY[Idx]))) # Update XY
nPart.SetOrientationDegrees (RefOri[Idx]) # Update Rot
if RefSide[Idx]!= nPart.IsFlipped(): # Current Side <> Reqd Side ? then flip
nPart.Flip (nPart.GetPosition())
print "Press 'B' when done, to refresh display & copper"
which is quite compact.
Seems to work, tho display refresh seems variable, & read-back checks seem ‘sticky’.
Next is to try & see if there is a PcbNew command line method to
a) first load a NET file then
b) run a Python script (above) on that loaded data set.