Is there a translation in MSA?
I was looking for a confirmation actually. Do you think لمض is a good option?
لمض means a person (especially a child) who who argues and talks back to adults, but who isn't too offensive or rude.
سليط اللسان is someone who use hurtful words, if not outright insults and offensive words, so it's different and much stronger than لِمِض (which can even be considered cute).
The problem with the word sassy is that its dictionary translations are always suitable to all context. I mean I found it translated as مَرِح but also as وَقِح! In some contexts, and using Egyptian Arabic, I feel the equivalent is شقي or , عفريت or even قرد. But I can't think of a fuS7a word for it.