Yes. Put the combined tool-and-part centre of gravity on both sketches. Comparing mass alone hides what that longer bracket has changed.

Can the fixture come towards the robot? That's where I'd spend the first ten minutes.

It can, if I change the loading side. I was treating its position as fixed when it isn't. I'll redraw that before touching the bracket.

That gives you two real arrangements to check against the FR3's load limits. 'Lighter' on its own wasn't enough to choose between them.