Wow this is an interesting find.
Cubs C, D, and E look to me like possible genetic outcomes for cubs of Kiara and Kovu while cubs C and D could also be cub versions of Mufasa and Scar. In fact cub C has a hind leg shape and muzzle very closely resembling Scar as opposed to Kovu who actually especially in adult hood seems slightly like a nonsense mix of Simba and Scar.
The muzzle of cub A resembles the genetics of Mufasa and Scar's generation oddly so if they or Simba had a sister she could fit the profile. Her body figure however resembles Nala, in fact I am pretty sure there is a promo shot of cub Nala with the EXACT same sitting pose, and body shape. The cub in the image even has the same eye shape.
In fact here is the Nala shot, I just found it on google:
So it seems almost like someone just took that shot and manipped the color and face a bit kind of as I did to create the marred Kopa in my fanart. I made a thread here with it.
All I did was took a shot of unconscious cub Simba in the original film and lightened his fur. Then I cut the mane tuft from a shot of Kovu and lightened it to brown and applied it to the Simba's shot's head. Anyone with basic photoshop skills can do it. Although I am not sure how to reshape the muzzle like that I am certain it must be possible.
At any rate if these cubs have no story or even names I disagree with the term semi-cannon. They were likely created to satisfy this game and there is a chance that it didn't consider the second film and the original does not have enough canon cubs.