Coppice, just a side note about Synesthesia.
I believe I have a mild, inconsequential form of synesthesia, I think called:
'Visual phantom Limb'.
The limbs are there, but when hidden, behind a blanket or table top, I can 'see' a shadowy form of 'hand', waving there unseen physically.
I've surmised that's just the brain synthesizing a crude likeness, in absence of actual light perception. Often, the movements are conveyed, but not coinciding with actual real hand waving there, in my informal 'tests'.
Just the brain supplying the missing info, which is perception of a Limb'. Those hand motions get seen by the eyes, what?, Some billions of times over a lifetime. So that makes sense.
Never diagnosed tho.