I will give you my opinion. The final determination is & must be with the FAA.
No certificated parachute component has any declaration as to chest/seat/back/lap.
Do you see any such declaration on a PD reserve? How about your reserve ripcord?
Re: 'What are those so-called "categories" officially categorized as?'
IMO they are not categorized. It does seem to me that this is a conflict within the FAA. They say that riggers have to be type rated yet the components are not marked as such.
Now, a reasonable person can readily determine a back parachute from a chest parachute. However, the actual components are not marked as such.
And, 'back in the day' some local FAA-types were requiring riggers to log their repacks of CrossBow rigs as chest packs. That is NUTZ IMO as the container was obviously on the person's back. IMO & experience, most FAA-types know little about parachutes, parachute regulations, and really prefer to stay that way. End of that rant.
Re: 'Or are you saying a change in harness is a Minor change no matter what the TSO?'
No. However, IMO the FAA is lacking in a substantive determination of just what constitutes a Minor Change vs a Major Change. John Sherman once told me only the actual designer can make such a determination. And, as I was told by someone in the upper mgt of RWS that when they developed the Vector container, they tested it & submitted as a Major Change. The Atlanta ACO looked at their paperwork and said that they considered it a Minor Change. This was because they were using the same materials, the same production methods, and the same Quality Program. Today, a Vector III says on the TSO label 'Wonderhog.'
As I have posted before, Derek Thomas purchased AeroSports USA. Jarret Martin purchased Summit Parachute Systems.
Does that answer your questions?
PS) George Galloway of Precision once told me that when the paperwork weighs as much as the component, the FAA will consider it a Minor Change.