Huh. I wonder if a resurrection would be possible if it involved a human sacrifice, or if it'd just end up with the soul of whoever you sacrificed being placed in the new body you created.
A resurrection IS possible. See Homuculi. The issue is you must do it before their soul leaves, which is to say it's only possible at all on the instant of their death.
You can go through the transmutation process again:
Step 1: Comperehension
-You know how their body works and approximate elemental composition. You can...while not recreate every detail of their body, get every detail that you know about down.
-You don't know how their soul works.
--If their soul is still in there? Cool, just fix it in position again(see affixing Al to the armor)
--If they are damaged to the point of soul loss? You could replace the lost soul if you already have souls on hand. Father, Hohenheim and the Homuculi all have an excess of souls to use for such repair work.
--If it's gone? You can only do it if you know how their soul works. Down to every detail.
It'd be like trying to transmute a painting into existence from the raw canvas and pigment, without knowing how it looked like. The information is lost.