It's taken a while, but the reworked shading on the stems - and so all of the embroidery - has been finished.
Here's half of the stems redone:
And the rest:
It's made a big difference, and I'm glad I decided to over-stitch the too-pale bits.
So that's all the embroidery done. The next stage in the process is not something I've done before, and it's making me very nervous. Wish me luck!