I've seen this more than once, but i was just hoping that someone would elaberate more on it.

After a battle, there is up to a 70 % chance that failed defensive facilities can be returned to use. (what does this mean?) Thanks in advance!

It means that if you get attacked and your defenses get destroyed, each defense structure has a 70% chance of coming back.

i think that the wording sounds like you have a chance of losing all of the defense but in reality 70% will rebuild, so it should say you only lose 30% of your turrets if you lose a battle, or 30% of the destroyed turrets in any battle

I thought it was a 70% chance for each individual structure. Not all of them grouped together.

it is each structure, and you dont always exaxctly lose 70%. I for one, have the bad luck of losing roughyly 35% if I get hit.