The Bugs(tm) intentionally letting their teeth pop out (much like how crocodilians open their mouths to regulate their temps) as a threat display has interesting implications for the concept of smiling. I imagine they show contentment or happiness by intentionally keeping their mouths tightly closed and fluttering their wings very fast, and a smile from a simian species like humans (who, now that I think about it, are the only species I can think of that bare their teeth out of *happiness*) reads to the uninitiated as a threat display out of the fucking nowhere
YES. so we did actually touch briefly on this before, but I think it's pretty common for aliens who haven't had interactions with humans before to have a visceral Hey What The Fuck reaction to seeing a human smile for the first time - Rhaxa and Imxa are both aware, to varying degrees, that this is a thing that humans do, and aliens who spend a lot of time around humans will get used to seeing/mimicking it, but it's definitely always weird for them. similarly, humans who spend a lot of time around them will get used to keeping their teeth hidden where possible.
since a lot of their language is pheromonal/touch/body language-based, I don't think there's necessarily one 'action' that can be directly translated as a 'smile' in the way we think of it - amusement, contentment, and happiness can all be expressed through different sounds, touches, claw and wing movements etc. definitely 'tense' emotions, even positive ones like excitement, can be expressed through lots of small, fast movements - wings and tails especially are good indicators of how they're feeling, as they'll tend to be a bit more conscious of waving their claws around, especially in human company.
once imxa's introduced you'll definitely see some differences between her and rhaxa and the way they express themselves, which I think might contextualise both of them a lot - both as very different personalities and as people with very different life experiences👀
