The problem is that the water in Ranquitte is very hard, and so minerals tend to build up on the rubber parts, and they don't "seat" well. That leads to leaking.
Over the ten months we were there, three teams (at least) tried to get it arranged to the satisfaction of all concerned. But since I was there, I got to see the three teams fail. In every case, the toilet leaked. That meant that I would shut off the water supply, and we would operate the toilet "by hand": that is, we would fill a small bucket with water, and pour it directly on the "contents" of the toilet to force the flush.
I finally realized that the toilet was fixed as it was! That's how that toilet was meant to operate. Sometimes you have to know when to fold 'em.