Hi guys the bones seem to be the main driver and the key shapes are like a smoothing technique… have you ever seen how on an elbo or knee how the skin flattens out like a balloon? would people use key shapes along side the rig to stop this unnatural behavior and no Daffrendo your not mad as far as I know the movements are subtle some are more obvious than others… as to binding these key shapes to bones there are many youtube videos how to do this in blender
Blender 2.82 : Everything About Shape-Keys (In 2 Minutes!!!) - YouTube
I am moving bones around in pose mode to fit my existing model as close as I can before I even think about sculpting. I will bake the final pose as rest pose before doing any edit to the mesh this should prevent any weird movements and also prevent the textures looking weird. the nose eyes and mouth need extra care the corner of the nose around the side bulges is a very easy place to get stretching of textures. pop in and out of the texture view to see that all the skin looks right use the normals to check stuff like the frown likes are sitting right and the crows feet etc there should be 3 movement sets and the plain face
extra note when moving the face bones !!! they are not all semetrical and you may want to find the root to each bone group use front and side view to align these then hide them so you know there done then start aligning the group bones in pairs the rig is set for the character and for more realisum been slightly deformed you can do this as a finishing step but there are a ton of bones not a quick job matching and aligning them at the start will make it more easy
sculpting without placing the bones first will move the weighted area away from the designed movement area may cause problems