Hi there and welcome to BYC!
Glad your bird escaped the attack..
Free ranging comes with dangers.. worry is a choice.. If you can't accept the possibility of a loss.. don't free range. Know it can happen at any time and take steps to avoid it.. but worry.. nah, life is too short for all that drama.
I like free ranging and choose to do so most of the time. There seems to be a high hawk season, maybe even twice per year for migration.. and sometimes I have to go on lock up so they see there is nothing here and they move on.. Most often chicks and bantams are easier targets. Some attacks get thwarted that we never even know about.
Like you said.. low bushes, lawn chairs, and other low things to hide under.. If you see the hawk.. blow it's cover.. they're ambush predators.. Keep blowing it's cover and harassing it with noise etc (within legal means, yes I look like a whacko flapping my arms, crowing, and being generally obnoxious) until gets miffed and flies away.. chickens have SHORT attention spans and quickly forget about the predator silently watching in a nearby tree.
Human activity helps SOME.. but they KNOW you are a slow moving ground based creature.. Limping and not walking chickens.. are easy prey.. Ultimately inviting predators.. AND disease (parasites, etc) to the flock.. It's a HARD choice.. but the main reason I don't/won't keep special needs birds... for informational purposes..
Fishing line strung across my Silkie pasture.. hadn't seen an attack since despite losing several chicks several days in a row prior.. anecdotal.. and sometimes a pain to keep high enough above my head.. BUT.. seems to have worked! I put a tall poll in the center and strung it out to the fence.
Hope this helps you think about what might work out best for your crew and set up and maybe even some tips to help them stay safe.