I think between #2 and #3 there is something.
#1 doesn’t translate well at the reduced size.
#2 seems to have a focus on the environment with the dominance of the tree. At the reduced size you lose the house and it looks like roots (which is kind of cool, but I don’t think you’re going for that.)
#3 & 4 at the reduced size looks odd with the plant. But the “ra” reduces best.
Also, with the semi-circle (#2) there is less stability in terms of balance. If the wind blows it looks like it will rock from left to right. A solid rectangle may give the mark more stability in that sense.
Maybe a solid black rectangle, with the “ra” inverted (white text) and then the house icon (minus the plant) on top (or if it’s required, maybe on the side and/or if you are going with the tree theme, I think an olive tree/branch would communicate better as pursuing peace, which is an aspect of their mission statement). The solid block would symbolize a solid foundation (with the “ra” representing the organization) and the house would represent rebuilding homes/communities–the overall mission of the organization.
Hope that is more helpful than not.