Cute Leon antics and all that, but I'm more surprised about Lumir.
Leon has a lot of room to grow if he's treated as a good dog, and taught new tricks. His visual memory is plenty to overcome illiteracy, and it's tragic he didn't think of it as an option. Is Canarium literacy that neglected? Historically, power structures literally need to make it illegal for groups to learn letters, else, basic literacy spreads. It's useful for basic shopping and passing basic notes. Ultra useful. So it's bizarre that an experienced traveler like Leon is both illiterate and surprised at the idea of being asked to learn some reading. Cute bonding moment though.
Lumir though is super trustworthy yet kinda sketch. Jelly is apparently a bizarrely talented slime, on top of getting goddess magic beyond what impious torturer Jelly showed. On the other hand how is finishing a jar of fruits a signaling mechanism? Magic? Goddess nonsense? This merchant demonstrated she and Jelly are breaking different rules or norms, and Lumir's body or self-study after gaining the body is definitely not a simple merchant. The least convoluted option is she's a mage or witch who chooses to be a merchant anyways. I doubt she's got plans beyond being a merchant though, because, as we see from how the slimes, slimes are simple people even if they use complex ways to keep a simple life. Like bodysnatching hobbits or something. (don't sleep on how weird the empty jar as a signal is, it's not a pricey artifact in itself)