I would be careful with what you read and trust on TripAdvisor, I have seen completely inaccurate postings... We have only been to CSA 6 times but to my knowledge no rooms there have truly open air showers. The atrium suites have the slat window in the shower from my shoulder height (6' 3") up, maybe this is what they mean?
The showers are not open air. There is no tub or lip at the enterance to the shower but instead the floor tiles slope inward so the water does not run out into the bathroom. There is also a shower curtain. The open air thing is probably some person's way of trying to describe it but in a misleading way.
We stayed in a villa room# 6007 at CTI and it had an outdoor shower, along with a small 4 foot deep dipping pool that could fit about 5-8 people.
The outdoor area was surounded by 10-12 foor walls/fence. Very nice and private.
How long ago was that? Those villas seem to all be offices or storage areas and not bookable for guests these days. They looked sort of nice (if they were repaired - they are in sad shape) but I would not trade a location in the garden for a view of the island.
We were there in April for our wedding on the island. Trust me we love the island, but the villas were MUCH nicer than any of the other rooms we saw that our guest had. Ranging from presidential suite to garden view.