They look great and almost done!
The yellowing you are seeing is the plant consuming the nutrients stored in the leaves. Which is an end of life process for the cannabis plant. Completely normal.
Canna flowers can feel oily, sticky, sandy, leathery, play dough like, all kinds of textures. This is completely normal.
It looks like you will have a very nice harvest of some very nice herbs!
One thing I would do is right before lights come on spray the plants down well with plain water. Just a good rinse before harvest as I see a few bugs stuck to the sugar leaves. No big deal as the buds look great. A little rain will do them good.
Let us know how she smokes!