To work with the RT/RD items you are best to disable auto crossfade,
also in File > Project settings > Advanced > Item mix behavior > Items always mix
you can also set this as default at the bottom of the dialog.
This will allow sections to play and ring out over the other item like a push rather than just playing top item:

Code
function print(value)
  reaper.ShowConsoleMsg(tostring(value).."\n")
end

if reaper.APIExists("SNM_SetIntConfigVar") then
  reaper.SNM_SetIntConfigVar( "itemmixflag", 1) -- Items always mix www.sws-extension.org
else
  print("Install SWS Extensions www.sws-extension.org")
  print("or manual set File > Project settings > Advanced > Item mix behavior > Items always mix")
end

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