There are a couple of things to note here.
First, are these townhomes relatively new? If so, then finding spiders in and around them is pretty normal. When the townhomes were built, they likely tore down some trees and leveled an overgrown area that was serving as living quarters for them. They come into the townhomes simply because they are looking for a food supply. If you destroy any webs and egg sacks you see, they will eventually leave and move on to someplace else to live. Spiders are not social creatures (hence the second word in brown recluse) and will move away from activity in order to find a quite place to set up a web.
If the townhomes are not new, then there is a definite problem. Something else is drawing the spiders in, which is not natural. It is strange for a spider to leave its natural habitat and move into the hustle and bustle of human life.
Another consideration to take into account is that it is very difficult to spray for spiders. You can spray down a web, but unless you get the spider itself, the spider will likely not be affected.
They do sell sonic devices now that are supposed to repel spiders and be safe for pets. You can try a couple of those in your living spaces, especially around doors that lead to the outside. That might help to keep the spiders out, and if it doesn't affect the cats then you should be okay. You can also go into places like garage corners and crawl spaces and knock down any webs you see. You don't have to get the spider - if you knock down the web chances are the spider will look elsewhere to build a new one. Eventually if you knock down enough of them the spiders will move out.
It's tough to do as an arachniphobe. When I moved into a newly built house they spiders were everywhere, including an absolutely huge wolf spider in the space above the garage (saw him in person a couple of times - about 6-7 inches across). They didn't bother me too much, but shortly after I moved in a friend moved in with me, and he was a serious arachniphobe, so I had to kill a lot of the spiders I saw instead of just taking them out to the woods to find a new home. Never saw anything too deadly, though we found what looked like a young black widow making a nest under one of the downspout splashblocks. Needless to say, that one didn't live - no sense tempting fate with those.
As for the legal aspects, I am not sure. Unless others in the block of townhomes have lost pets to the spiders, or have been attacked themselves, it might be difficult to prove a case. One thing to do in addition to documenting with letters is trying to capture one of the spiders just to show they do indeed exist. If you can't, then ask a friend that may not be so afraid of them to try and catch one for you. That way you have definitive proof that something much more menacing than a common house spider is present.