Here is OVA 10. The quality is quite bad but that's the quality CIAO uploaded in their youtube channel. I guess for that last bunch of OVAs (10-13) they didn't have good source anymore and did a bad upscale. Oh well, better than nothing I guess.
Chocolat no Mahou OVA 10 sub [MovingLines][720p] v2.mkv (51.1 MiB)