Hi. Well, whole back beans are not fermented, and I eat them all the time, so not sure wherre you heard they are not allowed. Black bean sauce or paste may be a different story. Also, all food issues, aside from the obvious no sugar, wheat or flour products really is individual. There is a lot of trial and error to treating candida, and very little "one size fits all".
To compound things even furrther, many claim success from actually adding in MORE fermented foods. I was not one of them, though.