It was our first time hatching, but here is what we observed:
We got 14 Ayam Cemani eggs .
We’ve purchase a Janoel 12.
(I made a slight modification to fit all eggs. -See picture)
During the whole time, humidity was between 60-70, we couldn’t lower it, no matter what we’ve tried.
We kept the incubator constantly at 37.5oC (Janoel12 doesn’t work with oF)
At lock down, we’ve filled the bottom with water as much as we could without touching the eggs.

Results:
On day 20: 6 chicks hatched after 6-12 h, 3 chicks took 18 and 4 took 24-26h from time I saw first sign of flacking.
1 egg was fertile, but it was very small, what I wonder might have been the problem, chick developed but did not make it. Nature’s selection I guess.