Okay, i understand better what you want.. in fact you 'd like a function RespawnInPolygon, so no such function in mist library.
you should write a new function for that..(possible but not easy to select a random point inside a poygon (good in math!!)...)
what i could to suggest you is to put circles zone inside your zone defined by the waypoint
you could put one or more circle to cover the zone (see the mission modified)
the problem with that is if you have 3 zones,if first have 10 circles and the second have 5 circles and last 1 circle (for example) you could understand if you use random zone, you have more chance to respawn in the first zone..
if you want equal chance between the 3 polygon, choice a random number between 1 and 3 and following the result respawn random in the circles of the polygon choosen
you can use the function math.random(1, 3) to select randomly a number between 1 and 3 and after you test the value and mist.respawn inside the desired zone..
hope you understand my poor english New Effort_1.miz