These LEDs were doomed the moment they were immersed in solution.
Copper plating killed the left one, and iron oxidation killed the right two.
Hot glue, shrink tube, and nail polish couldn't solve this. Maybe epoxy or enamel immersion, but I think the top photo shows a reasonable outcome. Just getting crystals in a flourette around the LED but formed to the size of an led is great.
My next attempt for this will be to make an led with a long wire insulated, sealed and pulled through the branches with a short negative leg either tucked into the tube, or solder bobbed onto the closest copper. Flux is a big risk, so I may do both depending on what kind of action I get to see what happens.
Current state: ready for renewal