Looks like the name of the artist is probably Stephen Peringer. That's what people on the Internet believe, including one who claims he flipped through a library book of '90s video game art where most of the SNES boxes were attributed to him. The resume on
his website mentions he did freelance for video game companies at that time. Sadly, there's no mention of Konami on his site or examples of illustrations for them, but the biggest thing that makes me think that maybe this is the guy is he did the box art for
Super R-Type (featured in his online portfolio), and despite being airbrushed, the head of the monster on it has a similar look to the kind of monsters on the Konami boxes, particularly the two-headed dragon from the cover of
Castlevania IV, or the dinosaur from
Turtles in Time.
Based on that little detail, and that some people are convinced it's him, it would appear that Stephen Peringer is the artist.
Now hopefully he'll reply to my email and tell me whether he is or not.