Well either it's going to be another hour or something is broken. Here's the version I've added in case it doesn't work:
#@gimp Multi Thresholds : tran_multi_threshold, tran_multi_threshold(1)
#@gimp : note = note("<i>Apply color to selectable tones</i>"), sep = separator()
#@gimp : Threshold_1 = int(50,0,255)
#@gimp : Threshold_2 = int(100,0,255)
#@gimp : Threshold_3 = int(150,0,255)
#@gimp : Threshold_4 = int(200,0,255)
#@gimp : 1st color = color(9,0,1)
#@gimp : 2nd color = color(175,42,27)
#@gimp : 3rd color = color(101,101,101)
#@gimp : 4th color = color(174,165,131)
#@gimp : 5th color = color(247,228,160)
#@gimp : sep = separator(), note = note("<small>Author : <i>trandoductin</i>. Latest update : <i>2016/08/25</i>.</small>")
tran_multi_threshold : -skip ${1=50},${2=100},${3=150},${4=200}
-repeat $! -l[$>]
-split_opacity --rgb2ycbcr[0] -channels. 0 -fc[0] ${5-7}
--fc[0] ${8-10} --ge[-2] $1 -j[0] [-2],0,0,0,0,1,[-1] -rm[-2,-1]
--fc[0] ${11-13} --ge[-2] $2 -j[0] [-2],0,0,0,0,1,[-1] -rm[-2,-1]
--fc[0] ${14-16} --ge[-2] $3 -j[0] [-2],0,0,0,0,1,[-1] -rm[-2,-1]
--fc[0] ${17-19} --ge[-2] $4 -j[0] [-2],0,0,0,0,1,[-1] -rm[-2,-1]
-rm. -a c
-endl -done