It is interesting what you have stated about brown jelly. This is normally something you only hear about with torch, frogspawn, and hammer coral. You are sure it was on your leather coral and it wasn't cyano
growing ontop of it?
Either way, in terms of keeping cyano
from returning you have started the corrective action. Aim for 0 nitrate and phosphate, cut back on feeding to prevent these number from rising.
In terms of the finger coral, see if it will blow off. If so, sounds like cyano
. If not and it starts to spread, it might be in your interest to cut those parts off of the finger leather. But we can cover that once we ID what is going on.