I was simply expecting a yes or no answer but I didn't get it. As far as I understand from what you've quoted from the dictionary に触るfor unintentional touch whereas を触るfor intentional touch. So I changed the particle にand をin my example sentences to ask for your confirmation in order to be sure of my understanding. I did gather that was not absolute and it has just been the tendency. Probably that was why you didn't give me a clear-cut answer.
Yes for "に and を are interchangeable", and no for your interpretation "intentional -> unintentional を -> に" or "unintentional -> intentional に -> を". Isn't this the same as;
"it's possible to say
意識的に(= intentionally)髪の毛に触った
or
無意識に(= unintentionally)髪の毛を触った"
?
There was a poet 斎藤茂吉, one of the most famous modern waka(Japanese poem) poet. His son 北杜夫 was also a famous novelist and essayist. Kita wrote an episode with his father in his essay.
When Kita was a collage student, he went for a walk with Mokichi. Mokichi suddenly stopped in a forest, and started to make a poem. Mokichi sat on a stump of a tree, and was thinking about which particle he should use in the poem, に or へ, with muttering. Kita silently left there, walked around in the forest nearly for an hour, and then returned to the father's place. Mokichi sat on the same place in the same pose, and was still thinking about which particle he should used, に or へ, with muttering...
If you just want to say "to touch something", you can use both ～に触る and ～を触る. What you want to say can be conveyed correctly in either particle since there is no significant difference in meaning between them. However, the difference can be huge for some people in some situation. The author of the book 日本百名山
を登る, which is mentioned in the thread linked above, intentionally chose the particle を. It is necessary to be を for him. (を indicates the purpose, not the location of moving, needless to say.)
神は細部に宿り給う
God is in the details.
I do have some question with the examples of climbing the mountain and climbing the ladder though. It says on the other thread that 山に登る has the nuance of getting to the top. I suppose it would be the same for the ladder and the roof, or even the slope.
The point is that 山 can refer to both the top of a mountain and the whole mountain, therefore 山に登る and 山を登る are both possible. 階段に登る is odd since "ladder" is not the destination when you climb a ladder. The same goes to slope or roof (roof is the destination, and not the location of moving, except a special case like I mentioned in the thread I linked).
What if one wants to say going up but not all the way?
Just 階段を登る or 坂を登る. Even if the final destination is the fifth station of a mountain, 山に登る is valid.
山に行く or 山へ行くmean getting to and going to the foot of the mountain only, don't they?
No. both mean "to go to climb a mountain". Think about sentences like 映画館に行く, レストランに行く or デパートに行く. You usually go to a movie theater
to watch a movie, and not just go to the entrance of it, don't you? In the same sense, if a mountaineer says 来年はエベレストに行く, it means he/she is going to
climb Mt. Everest next year.