Hi there. First off, welcome to the forum, and thanks for taking the time to provide some feedback!
1. Stop waiting for overload. If hard flux is almost maximum, vent. If I have 2 or 3 capital ships I don't like swapping command between them just to tell them to vent flux and not overload.
This was more or less addressed in earlier posts, but I'll just add that overload is often preferable to taking a missile or torpedo hit. When your hull is low, it's also marginally preferable to venting only to die from incoming fire in a second or two. Waiting to overload does get the absolute most out of shields, PD, and soft flux dissipation.
Simply venting when hard flux is high is very problematic - you miss out on chances to use PD to shoot own missiles, firing on an an enemy that's themselves venting, etc. There's really no easy answer as to when a "good" time to vent is. Any answer that seems easy and simple is likely the exact wrong thing to do in some circumstances
2. Venting is far less dangerous if you go in reverse, away from the enemy. Sometimes that is so successful that you take no damage while your shields are down, even with slow capital ships.
Ships will pretty much always do this. Or try to, unless prevented by outside circumstances.
3. Less damaged ships should try to get in the way of people targeting heavily damaged ships.
There's some logic to do that in relatively narrow circumstances (basically, spontaneous "escort" behavior, without that command being given). In general, though, ship cooperation is a tricky thing to get right. They do some basics such as spreading out, trying to avoid getting in each others way as much as possible, etc.
If I can make a request - AI feedback is most helpful when accompanied by (at least somewhat) reproducible circumstances when the particular behavior occurs. It's complex enough that just because <behavior X> happened, doesn't mean that it always happens. In fact, it may never happen except for a specific ship loadout/opponent. So, if you point out a specific matchup and say, <problem X happens here>, that's really something I can bite into and possibly improve. If not, chances are I won't even be able to reproduce the situation.
(For example, point #2 above seems to imply that you've run into a situation - perhaps numerous times - where venting ships don't also pull back. They're, however, coded to do that, and in my experience, do. Without specifics, I really don't have anything to go on there.)