Well, since you asked for it, I'll throw any comments at you I can think of ATM, see for yourself if they make sense
For clarity, I will call the stuff above the connection node the conditions, and the stuff below your actions.
So first of all: the conditions seem to fit nicely
in your actions, I don't understand the purpose on some parts. Why do you have the part where you attack an easy killable enemy if you are almost killed yourself? I would at least make sure that 1. You are only being attacked by 1 enemy and 2. That enemy will die sooner than you. Otherwise, you may attack when you should be fleeing, and this way, you can flee even later if it's a one on one.
Second: in your last action: why flee from out of range units?
Third: if you're close to the wall: you start attacking without a check. (Even for the range, instead, you could put a simple attack subtree in there.)
For the conditions: you might want different actions resulting from the conditions: attacking a weak unit/attacking if close to the wall, instead of fleeing/moving somewhere else, is suicide if multiple enemies are attacking you. Furthermore: do check the range of multiple enemies.
Next: checking if an ally exists is nice, but check if he is of any help too (range, hp, shield?). Also: why flee earlier if an ally exists?
This should at least get it somewhat further concerning what you already have
To get you further than that: try to structure your action part and condition part in such a way that it is easy to add specific scenarios to your fleeing module with different actions as reactions. (Flee earlier with a mg than an as or sg for example.)
