I have some doubts:
1-The hability 'Tailwind' of Yip serves for all the archers of your army, or only those that are within the wind ..
2-For humans: Yip or Elena ?
3-Sometimes my archers die in a easy siege.. Why can it be ? Is it possible that i let a gap in my frontlines or similar ?
1. Only the units in the graphic effect.
2. Elena > Yip in my opinion, but both are great.
3. Leaving a gap in the middle can cause AI to target backlines first. That said, sometimes the AI just targets backlines. I've run the same setup 20 times, and depending on the type of troop I am fighting and the corpse it leaves, it can shift my units around and cause my backlines to be exposed. Cavalry also tend to skirt around your frontline and hit backline units. It also sometimes just seems to arbitrarily target your backline from the start. Shore up the best layout you can and hope you don't have issues.