Looking at the screenshots, I think you once called it the "teeth chattering effect"?
Combing, mice teeth, interlacing ... these words are all referring to the same phenomenon where field 1 and field 2 have 2 different images in them (as they are supposed to have by design). This is definitely not the case in any of the screenshots, but there is field alignment issue and that will be made more visible by sharpening.
How I like the the image to look is not necessarily what anyone else will like. Some release groups add their own sharpening to their videos and imo that is a bad decision - better to let the user decide how much sharpness they want (unless it's artistic intent of the director/producer of the content).
The problem scenes...
"Prince of Wails" with the humvee
The PAL version is softer and doesn't have those high contrast 1px pattern on the Jeep grille to begin with - they've been smudged out by whatever equipment Universal used to create the PAL version. If the PAL version was sharper and resolved all the resolution in the grille, you would get the same issue with TFM detecting the grille as combing and switching to bwdif for those frames which causes the issue with moving parts of the image dropping to interpolated 240p with aliasing / twitching on moving pixels.
Perhaps you would prefer some stronger QTGMC repair smoothing:
QTGMC(InputType=1, preset="slow", Sharpness=0.0, FPSDivisor=1, EdiThreads=CPUcores/2)
# medium smoothing
QTGMC(InputType=1, TR2=2, preset="slow", Sharpness=0.0, FPSDivisor=1, EdiThreads=CPUcores/2)
# high smoothing
QTGMC(InputType=1, TR2=3, preset="slow", Sharpness=0.0, FPSDivisor=1, EdiThreads=CPUcores/2)
# max smoothing
QTGMC(InputType=2, TR2=3, preset="slow", Sharpness=0.0, FPSDivisor=1, EdiThreads=CPUcores/2)
Although the image will look pretty soft at max smoothing so you might need to set Sharpness to a nonzero value.
"Fever" in the pharmacy
If it's this scene then it's the same issue as the Jeep grille
"Eggheads" with the houses
Again same issue as the Jeep grille - TFM sees legitimate image data as combing.
"Last Days" streets
That section has a completely different issue - the studio deinterlaced that section to 30p using their own bob-weave filter similar to bwdif in Avisynth. Because the camera is wobbling ever so slightly it keeps creating small amounts of motion that keeps tripping their bwdif into bob (interpolation) mode for moving parts of the images - all the twitching / flickering lines are pixels dropping to 240p for a split second. QTGMC repair mode works wonders on that section - video here
And my Universal question for pneumatic was really: the videotape files are fuzzy and blurry. You've been able to clear up the distortions significantly and add a bit more detail. Do you think that the files can become sharper via your scripts or other third party sharpeners? Or are we pretty much at the limit of how much these files can be improved?
It's hard to say as it depends on the subjective quality of what you prefer in the image. If the PAL/Turbine version looks better to you then you'd want to investigate smoothing the image more with those QTGMC settings, and then if the image looks too soft, adding some sharpening.
Another option is to just QTGMC deinterlace instead of TFM+TDecimate but you'll get moire on high contrast 1px patterns.