Suntria and Sprout's big eyes and simple color schemes make them decently expressive and fit with the tone of the first half of the episode, but not with the violence later on. It's kind of like seeing a baby bunny maul someone to death; it can't be anything but comedic.
Also, the overabundance of the sound effects detract from the experience, giving every little motion a wacky noise even when the characters are in mortal danger. Everything's emphasized, so nothing is.
Still, it does tell a complete story and has decent animation. Plus it keept my attention until the end, so it's not bad, just awkward.
Please continue to make these shorts. I'm sure a lot of people would love to see where this goes.