The LARGE pool is totally enclosed in six foot stone walls and bug-cage. Can harmful gases accumulate from salt to chlorine conversion and can harmful gases linger in an enclosed area?
A salt water chlorinator does not produce chlorine gas (it uses the salt in the water to produce hypochlorous acid and sodium hypochlorite: source). Moreover, the process takes place under water in an enclosed container. You therefore shouldn't have any fear of harmful gases from that process.
Furthermore, the smell that poolgoers usually associate with "chlorine" isn't actually due to chlorine but to chloramines (byproducts of chlorine sanitising organics in the pool) which indicates a lack of free chlorine in the water. Because salt water chlorinators can produce free chlorine continually, you don't usually get the "chlorine" smell with salt water pools.
I am not aware of any problems, I used to teach scuba at a fully enclosed pool that used the platinum wire and electricity to create the chlorine. I liked it so much I put a system on my pool it is really easy on the skin. Make sure you purchase a large enough system my first one was undersized and could not keep up with all the kids and grand kids but that pool is outside so I never saw anything there either.