I like it. Very close to the original cases. I prefer the one without the red on the spine. I like the plain text spine, but that could be because all but two of my games are like that. The one very slight criticism, if you could call it that, is that the font is different. But I don't imagine it's easy to find out what font they used.
Would it be possible to add a second type to the template modelled after the other style of case? I mean the one with the black spine which has a red stripe through it, and a yellow 'Mega-CD' in a different font to the one you've done. The game title is also in a different font and colour. They also have a very different front, without the side and bottom borders. Or is this what you meant by the 'both types of Mega CD logos'? If so, never mind.

It's not a big deal if you don't add it, and I'm not really sure if I'd prefer to have those ones be as close to the originals, or just keep them all in a uniform style.
And could you add Mega-CD 32X as well? It'd be a bit more effort with the stylised spine and border though.
Anyway, I'm looking forward to this template getting completed. Thanks for working on it.