As someone who has done a huge amount of research into the Amiga version, I will state that I do not believe that version was ever commercially released. No box scans exist of it anywhere, and the ROM that exists by novotrade does not match the screenshots on the back of the CVPC box, which shows the Commodore/PC/Amiga versions.

This ad exists, but shows no different screenshots than the back of the Castlevania PC box. Furthermore, a ROM dump of the version actually advertised does not exist. Only the Novotrade version, which looks vaguely like the PC version, but is quite arguably the worst Castlevania game ever made. My suspicion is that the Amiga version was canned before it even hit the shelves.

I still have hope there WAS an Amiga version actually sold, but until I see box/disk scans I will remain extremely skeptical.