In case anyone is still wondering about this,
Nonesuch (her author) posted a short explanation in his own
thread:
Unsure if this is a bug or not but Jasvalla actually appears in Mhen'ga when the PC is level 2-3.
This is the code to determine if Jasvalla is at Mhen'ga
JavaScript:
if (jasvalla.met() && !jasvalla.atTavros() && !jasvalla.imprisioned() && pc.level >= 2 && pc.level <= 3 && (!flags.JASVALLA_ENCOUNTER_TS || (GetGameTimestamp() - flags.JASVALLA_ENCOUNTER_TS) > 600)) choices.push(window.JasvallaMhengaEncounter);
I doubt any people will notice though since most people first level up just after First-14.
Other than that Jasvalla will only show up at Zheng Shi if the PC is level 9-10 (Quite clearly, this isn't a problem since the level cap is 10 but this might mean that when level 11 is added she might move somewhere else, like Dhaal, maybe?)
Code for her Zhéng Shi encounter:
JavaScript:
atZheng() {
return jasvalla.met() && !jasvalla.atTavros() && !jasvalla.imprisioned() && pc.level >= 9 && pc.level <= 10 && (!flags.JASVALLA_ENCOUNTER_TS || (GetGameTimestamp() - flags.JASVALLA_ENCOUNTER_TS) > 600)
}