Switzerland Sitting Helvetias - Fake Cancels?

Last weekend I was looking through my stockbooks and found some early Swiss stamps I had squirreled away to eventually delve deeper into their provenance. I'd forgotten about them. Not wanting to forget about them again I scanned them and displayed them below.

I'm pretty sure I've correctly identified them correctly. They all "seem" to be postally used, however I have my doubts about some and would like a second opinion. Condition is mixed, so don't focus on the flaws.

I. 1862-64, white wove paper
Faking cancels on any of these except the 3c black would be unlikely as the unused prices are generally much higher.

a. Left to right, Scott 41, 42, 43, 43a, and 44
Michel 20-23






b. Left to right, Scott 45, 45, 46, 47, and 48
Michel 24-27






II. 1867-78, white wove paper
The 15c lemon, especially, and 40c gray are likely candidates for fake cancels. The back of the 15c lemon shows original gum, and has a suspicious cancel. Anyone concur?

a. Left to right, Scott 52, 52a, 53, 54, and 55a
Michel 29-32






b. Left to right, Scott 56, 58, 59
Michel 33-35







III. 1881, paper with colored fibers (granite paper)
Scott 66 and 68
Michel 42 and 44

Both likely targets for fake cancels. The date on the 1fr looks suspicious doesn't it?

The 40c has only a handfull of paper fibers visible on the back, mostly dark fibers, and none visible from the front, unlike the 1fr, which is undoubtedly granite paper. Is it possible to fake fibers by pasting then on the back? I can probably pull the most prominent fiber off the back of the 40c with tongs. The date in the postmark on the 40c is contemporaneous with issue date.