Another accepted answer as of now is "If she didn't walk he wouldn't see the animals." Is it really possible to switch the (unstated) subject like this without actually indicating it?
I note the change from "If he were not to walk, he would not see the animals". I prefer the didn't format, but it would be good to know when each translation format can be used.
Both should always be accepted. While if he weren't to is stilted, it is grammatically correct. Lack of consistency in this course drives me crazy.