I don't think that the schematics are wrong.
In fact the capacitor in this image

is strange. The - arrows point in the direction of the narrowing, opposite to the usual way. Since the visible right side of C9 seems to be metal, I would assume that this is the GND side.
To sum it up, I think
- the right side should be minus
- the arrow on the capacitor in the image above is wrong
- the capacitor in the image above is mounted correctly (+ left / - right)
- the silk screen on the pcb seems to be wrong
I am not an electronics expert, so please convince me that I am wrong.
