Agree with ID on R. cereuscula, it is one of the more distinctive ones. Hard to describe the growth pattern and the description would make it sound similar to others, so I won't try here. After a time, you will be able to ID it when you see it. Cereuscula like water. Cuttings start easy and will also start in water. When actively growing, be sure to keep soil moist. This one seems to respond well to gentle root fertilization, as well as foliar, but don't overdo it. If its not growing well for you consider fertilizing or transplanting, but based on the pics you posted, I don't think it needs replanting.
I am about 80% sure your "R. ewaldiana" is actually R. sulcata. The distinguishing factor between the two is how the stems grow and fill out. Look carefully at the longer stems. You should notice that the longer stems tend to have a bunch of shorter, terminating stems, maybe two or three inches long on them. This is seen in your third picture of that plant above. [the growth pattern can be compared with that seen with R. mesembryanthemoides, although that one does not look at all similar to sulcata or ewaldiana. The terminating stems on mesembryanthemoides are much shorter and more densely packed together.] Ewaldiana does not do that.
Capiliiformis is one that I have seen over the years be mis-ID'd frequently to the extent that I am no longer sure which one that is. Angel Plants grows a "trailing Rhipsalis" that sometimes bears this name, I have another one from a different source that also has that name, but is different in growing vegetatively. There is also one labeled "mophead" that is one of my favorite Rhipsalis that may be a form of the "trailing rhipsalis" grown differently. Stem sizes are very similar between the two, but one branches frequently while the other sends out stems two or three feet without branching. I seem to be unable to keep the "mophead" one alive more than about 5 years. Mine slowly decline, perhaps because of low humidity during the winter.
Rhipsalis.com is the best site out there for Rhipsalis information. The descriptions on that site are direct quotes from the scientific literature and they (Ken and Derek) a serious effort to keep up on changes and keep accurate pics. Unfortunately, they are funded out of their own pockets, so do not have the funds to post bigger pics or keep a larger site. But that is where I go when trying to ID a Rhipsalis, Lepismium or close relative.
Can you get some more pics of your capilliformis? With Rhipsalis, closeups of flowers, fruit and stems are needed, as well as pics of the whole plant. Always get pics showing flower structures and fruit when opportunity presents. Where you can, put a medium blue cloth behind the flowers for pics. This helps show the true colors.
I'll try to post some pics on this thread in the next day or two.
