Based on my experience you can only do so much to make the datnoid comfortable. Sometimes, its just depends of the fish. I have a total of 7 datnoids, 2 silvers, 2 NGTs, and 3 indos. All the indos are stable except for the biggest indo which is 3.5". The other indos are 2" and 3". I've had the biggest indo for close to 3 months.
My silvers and NGTs took 2 and 3 months respectively before they became stable. My tank has perfect water parameters, 82F, had driftwood as hiding place, and fed everyday. Its bare bottom as well.
All I can say is do what you have been doing all along and the indo will eventually become stable. You can only do what you can and if nothing still happens, just wait it out.