Speaking of tricky, this one was a problem. See I think what's happening here is Sep is ignoring Cloud in the scene completely (it certainly looks that way), and so the actual translation is:
Sephiroth
“Mother…
Let's reclaim the planet.”{NEW}
“I have a great idea.
We'll head to the Promised Land.”
------------------------------
{CLOUD}
“Sephiroth…”
------------------------------
{CLOUD}
“My family!
My hometown!
How could you!?”
------------------------------
Sephiroth
“Ha,ha,ha!
Here they are again,Mother.”
------------------------------
Sephiroth
“With your superior abilities,
knowledge,and magic,you
were destined to rule the
world.”
But they...
Those worthless fools...
have stolen the planet from you and your people.
You need not be sad any longer.
as opposed to:
Sephiroth
“Mother, let's take the Planet
back together.”{NEW}
“I've thought of a great idea.
Let's go to the Promised Land.”
------------------------------
{CLOUD}
“Sephiroth…”
------------------------------
{CLOUD}
“My family! My hometown!
How could you do this to them!?”
------------------------------
Sephiroth
“Ha, ha, ha…
They've come again, Mother.”
------------------------------
Sephiroth
“With her superior power, knowledge,
and magic,
Mother was destined to become
the ruler of this Planet.”
But they...
Those worthless creatures
are stealing the planet from Mother
But I'm here now
So don't worry.
Remember that Japanese does not indicate a difference between the name and "you"/"your", well not from what I've seen. I asked Luksy before and he said there was no way to tell. The scene as is certainly goes to the side of him speaking to his mother alone, and the text beforehand indicates he has no intention of talking to cloud.