@ozia:
I have a task to do precisely 2.3.2 on ZFS, how can I do this?
Your task is not possible. The ZFS installation options were removed from 2.3 because they did not fully work properly, and we did not test or verify their functionality so manually configuring it has undefined, but potentially broken, behavior.
We added them back in 2.4 because we switched to the same installer used by FreeBSD and it was stable there.
Using ZFS on any version prior to 2.4 is not supported and is most likely going to not work or be unstable.
If it was going to work, the procedure you followed was your best chance. Since that didn't work, you're out of luck.