Zoom with the trackpad on MacBook behaves uncontrollably in Final Cut Pro.

Yes, zooming FCP timeline using the trackpad is often wildly inaccurate. Alternatively you can use command-plus or-minus, or press Z for the Zoom tool, and click.

I love trackpads, I hate mice. I use a Magic Trackpad and find it way more accurate and nicer to use than my MBP built-in trackpad. It works fine in FCP. But that said, yes, I've always noticed that using a trackpad in FCP is way. more sensitive and inaccurate than any other app. My only solution for you is to get a Magic Trackpad. Which defeats the whole purpose of your MB trackpad. Yeah, FCP has never handled trackpads as well as other apps.

When zooming in or out significantly like a linked video, I think it's better to use ⌘+ or ⌘- instead of the gesture. Shift+Z to display the entire timeline.

The trackpad gestures are suitable for slight enlargement and reduction, so I think it's sufficient if they work near the cursor position. I think it's better to change to an app you like instead of sticking to gesture zoom or getting stressed out by comparing it to other NLEs and looking for flaws.

I'm not sure what you want your link video to show. What do you want to do with the gesture? What kind of movement does "smooth" specifically refer to?