Playing the lastest ATM9 in single player , found 2 issues about the Rainbow Furnace. The lastest ATM9 use Iron Furnaces mod in the Version of 4.1.3, and I update the mod to Version 4.1.5, but issues seem to exist in both version.

I use Smoking, Efficiency and Generator Augment in the Rainbow one and all other furnaces it requires, also put them into redstone toggle mode. So that they can use food to generate RF with redstone control.

1.After the Rainbow Furnace is triggerd, when all the furnaces are turned off by redstone signal, the rainbow one still output 50000RF/t, without causing any food or fuel. Free power! Yey!
2.After go thought the portal in the End and go home, the Rainbow Generator somehow cannot generate 50000RF/t any more. Break and replace the Rainbow Furnace will NOT fix the issue. Have to break all the furnaces and replace them, then they will work again. Using the Waystone mod to teleport between the Overworld and the End won't trigged the weird shotdown.

Not sure if issue No.2 is cause by the Iron Furnaces mod itself, so I post here. Have a nice day.

Noticed this behavior in All the Mods 9! Really threw me off until I found your comment here.

Thanks @zilla0088 !