From the sounds of it, though, none of them are in the habitable zone for their orbits because of how close they are to TRAPPIST-1. The inner two? They might have habitable regions, and the outermost (with the unknown orbital period) might be habitable considering that it "probably" gleans less radiation than Earth does from our sun.

Come May 4th, astronomers will be able to get a better look at TRAPPIST-1 and measure two of the planets as they transit the star via the Hubble telescope, analyzing their atmosphere and seeing if there are any bits of water vapor present. An extended campaign will give NASA a chance to study these with the relatively new James Webb Space Telescope's infrared capabilities to further study their atmospheres.