Yes, if your flee fails, for what ever reason, or if as sometimes happens, they follow you when you flee, they can continue to hit you. (Aggravating to not have trap aware and be stuck unable to move for minutes after having won the battle, but such is life.) *Peers at Kvetch* There are some rooms that one can't can't flee or retreat from with tough mobs. *Grin*
How does anyone train a spell to 99 percent? As far as I know the maximum is set to 98 percent for mortals, exception being some species are "born" with 100% like centaur with 100 percent ride and mount. *Laugh* Not much use as they can't do either.
I have had the lost concentration on casting heal 3 or 4 times in a row, (after which death occurs, if not before), which is possible at < 2% occurrence but not very likely. This happens both when casting on self or on others. I will try and remember to log some occurrences and post them. Just as a quick check used a spell that I only had only trained to 80% 100 times with no fails and in the process trained it up to 83%. Then cast heal, (not in battle), trained to 98% 100 times and had 4 failures for loss of concentration. As the results should be random doesn't really prove anything. To small of a test to satisfy the rule of large numbers.
Also spells have a chance of missing target, (just like melee can miss the target), or not producing any results, (you cast the runes of <spell>, but no damage or miss message), as well as failing from the caster loosing concentration. If it matters my accuracy is 327, it seems to be capped there as it hasn't increased in many remorts, (don't know if that is only improved while melee or not).