> Unfortunately, they do need to be re-generated, or you will get what you see: The old file with the new picture.
Ok, I regenerated Kate's help files and the title now looks ok (white color, on the leftish side).
But the bottom part still shows the old blueish KDE color and the horizontal ribbon as well. I can post a screenshot if required.

> When are these files generated? At build time or the first time they are open?
They are generated at build time, often stored as a zip archive.

Cheers
  Michele