Whale Teeth

it makes perfect sense for the whale to have teeth.

The whale's species is, to my knowledge, never identified; but as far as real-world non-fantasy whales go, a blue whale or a humpback whale wouldn't even be physically able to swallow someone Rosella's size. The only real-world whale that plausibly could is a sperm whale, which also happens to be the largest whale with teeth. And the color and the head shape of the KQ4 whale also match a sperm whale well.

(That said, a sperm whale's teeth look nothing like those in KQ4. The teeth on a sperm whale's lower jaw are much thinner, and the upper teeth are rudimentary and usually hidden. There have been extinct relatives of the modern sperm whale that did have full sets of teeth on both jaws, but again, the teeth were fairly thin with visible gaps between them. And a sperm whale's stomach looks even less like KQ4; so my guess would be that we're likely dealing with some wide-toothed sperm whale relative unique to Tamir.)