Please help identify the problems and hopefully offer solutions on my ailing Epiphyllum German Empress and on the Thanksgiving cactus. I removed most of the sick leaves, but not all.

I am in Canada, many products are not available here. I use mostly natural pest control...

1) Re: pics #1,2: Two years ago I received the epiphyllum German Empress with a couple of limp and discolored leaves. Was told that it was sunburn and it would disappear. Didn't but new leaves grew and the plant bloomed nicely last summer when it was outdoors. Recently I noticed some small round brown /black spots mostly on the limp leaves but also on others including young ones, and other leaves are shriveling up too, some with damage on the edges. .. Would it be scale infestation? Or fungus ?

2) Re: pics #3, 4:The Easter cactus has some small round spots too, similar to German empress, but they appear to be more pale, and in the interior of the leaves.

3) Last pic: Several of my Thanksgiving cacti have different kinds of spots, lighter brown, almost like rust. What could it be?