Spine cards are usually quite important for those who collect Japanese CDs (not just games, but music CDs are this way too) so yes the Spine card should be there if we can get it. But it is also understandable that sometimes we cannot find a good picture of a game with the spine card in, or we may have games without them (I know I certainly do).
I would say the appropriate image types would go in this priority:
1. Image of front including spine card. This is how a sealed game would look.
2. Image of front including full jewel case if the plastic jewel case inlay is *not* plain black plastic (or the standard release container)
3. Image of the front insert/manual
The above is true for most game releases including things like PS2, Nintendo 3DS or whatever. We would want a full front shot for PS2 games that did not come in the black case (blue EU releases, red Greatest Hits, etc), Nintendo 3DS had some games that came in a red case, etc. Or Dreamcast games that were released under the All-Stars imprint where the manuals are the same as the normal release.
Now for identification purposes, many people are not aware there are different versions of a game, or a person may think we have the wrong picture if they do not have or know what the spine card is for. It may be worth noting on the Virtua Fighter Kids item Description field that the jewel case has a clear inlay and it says Virtua Fighter Kids in the insert which is viewable on the front edge. Toshinden S has the black inlay, which is common and doesn't need to be noted.
Regarding the back cover image, the pictures you have been uploading are what the back cover were to look like if it was removed from the jewel case and flattened. It shows the edge parts. This is fine for an entry where no picture exists, but if one already exists (and is correct) it should not be replaced with one showing the edges. I said "spine" to mean the portions of the physical back cover that appears on the spines of the jewel case, not the spine-card itself.
PS: for anyone reading these posts and wonder about a spine card. In Japan, a piece of printed paper is put onto the edges of a CD sold at retail containing the product name, sometimes the price and usually the barcode. This is why you find a lot of Japanese CD games not having a barcode on the back, because it would have been on the spine-card. For collector's purposes, the spine may or may not have been glued onto the jewel case at manufacture, so if a new item is removed from shrink-wrap, the spine card may also fall away. It is easy to be damaged or lost, which is why you will find CD releases with a spine card to often be sold or worth more than ones without. Spine-cards were also used on some Japanese LaserDiscs and perhaps other media types as well.
