Cura 5.2.1 and retraction, and do I have the dumb?

Cross-posted from r/3Dprinting:

I wanted to print a retraction tower, as I've never printed one. I experimented a little early on but mostly I've just found best temperatures and that's worked pretty well for me.

So I installed the Cura plugin to generate a retraction tower and set up the script to change the retraction settings on each level and all that, all as described here. It's an older video but the instructions all still work.

Now I can tell that the script is actually running because it's adding in the display message, showing different retraction distances. But there's no visible difference between levels on the tower, and more importantly, I can't find any indication outside of comments and display message that it's actually setting retraction distances at any point.

Here's a chunk of code from one of the generated .gcode files, with all G0 and G1 stripped out for legibility. And as you can see, the M117 commands are telling the display to show different retraction depths. But what I don't see is any command to change filament retraction amount from 4mm to 5mm:

;LAYER:156
M117 retract E4.0
;TYPE:WALL-INNER
;MESH:RetractTower
;TYPE:WALL-OUTER
;TYPE:WALL-INNER
;TYPE:WALL-OUTER
;TYPE:WALL-INNER
;MESH:NONMESH
;TIME_ELAPSED:2421.802687
;LAYER:157
M117 retract E4.0
;TYPE:WALL-INNER
;MESH:RetractTower
;TYPE:WALL-OUTER
;TYPE:WALL-INNER
;TYPE:WALL-OUTER
;TYPE:WALL-INNER
;TYPE:WALL-OUTER
;MESH:NONMESH
;TIME_ELAPSED:2434.206011
;LAYER:158
M117 retract E5.0
;TYPE:WALL-INNER
;MESH:RetractTower
;TYPE:WALL-OUTER
;TYPE:WALL-INNER
;TYPE:WALL-OUTER
;TYPE:WALL-INNER
;TYPE:WALL-OUTER
;MESH:NONMESH
;TIME_ELAPSED:2446.615042
;LAYER:159
M117 retract E5.0
;TYPE:WALL-INNER
;MESH:RetractTower
;TYPE:WALL-OUTER
;TYPE:WALL-INNER
;TYPE:WALL-OUTER
;TYPE:WALL-INNER
;TYPE:WALL-OUTER
;MESH:NONMESH
;TIME_ELAPSED:2459.024074
;LAYER:160

More, I don't see any commands involving retraction at all, other than a G1 towards the beginning which includes a -6.5mm retraction - my default retraction at the moment, from experimentation some months ago. Since then, I've been handling any stringing issues through temperature changes only, finding the best print temperatures.

G1 F1500 E-6.5 

The only other negative E commands are a pair of retractions at the very end of the .gcode file as the printer is finishing the job and shutting down:

G1 F2700 E-6.00000
G1 E-2 Z0.2 F2400 ;Retract and raise Z

There are literally no other negative-direction commands on the extruder at all, and as far as I've been able to see no attempts to move the extruder backwards in absolute numbers either - relevant since the .gcode has the printer in absolute positioning on the extruder most of the time. All the other E movement commands are positive increments except for the three negative numbers I've included above.

Also, there are no G10/G11 commands in these output files, etc.

So do I have the dumb? How is retraction working here? Is retraction working here? At all? Have I just been getting by on temperature adjustments? Is that G1 F1500 E-6.5 somehow magic and sticky in ways not described by the Marlin firmware guide?

Anyway, I'm really confused and I've done more than nothing. What am I missing?

ps: Here' s a sample chunk of code showing E line only goes up. But it's all like this as far as I can tell.

G1 F918.7 X121.555 Y112.851 E1427.40228
G1 X122.173 Y112.982 E1427.42302
;MESH:NONMESH
G0 F300 X122.173 Y112.982 Z39.4
G0 F9000 X122.215 Y112.586
;TIME_ELAPSED:2957.771081
;LAYER:196
M117 retract E6.0
;TYPE:WALL-OUTER
;MESH:RetractTower
G1 F600 X121.679 Y112.474 E1427.44124
G1 X121.185 Y112.253 E1427.45924
G1 X120.743 Y111.931 E1427.47743
G1 X120.381 Y111.531 E1427.49537
G1 X120.103 Y111.042 E1427.51408
G1 X119.94 Y110.541 E1427.5316
G1 X119.886 Y110.025 E1427.54886
G1 X119.94 Y109.461 E1427.5677
G1 X120.102 Y108.962 E1427.58515
G1 X120.38 Y108.472 E1427.60389
G1 X120.758 Y108.057 E1427.62256
G1 X121.186 Y107.746 E1427.64016
G1 X121.679 Y107.526 E1427.65811
G1 X122.215 Y107.414 E1427.67632
G1 X122.755 Y107.413 E1427.69428
G1 X123.29 Y107.526 E1427.71247
G1 X123.785 Y107.746 E1427.73049
G1 X124.227 Y108.069 E1427.7487
G1 X124.599 Y108.488 E1427.76733
G1 X124.849 Y108.919 E1427.7839
G1 X125.029 Y109.457 E1427.80277
G1 X125.085 Y110.017 E1427.82149
G1 X125.029 Y110.54 E1427.83899
G1 X124.859 Y111.058 E1427.85712
G1 X124.589 Y111.529 E1427.87517
G1 X124.227 Y111.93 E1427.89314
G1 X123.785 Y112.253 E1427.91135
G1 X123.269 Y112.479 E1427.93009
G1 X122.755 Y112.586 E1427.94755
G1 X122.215 Y112.586 E1427.96551
G0 F9000 X122.132 Y113.38
G1 F600 X122.837 Y113.38 E1427.98896
G1 X123.538 Y113.231 E1428.01279