I don't know what's wrong with Lato at 400 weight. Its either the rounded extra-wide dot or something else, but Lato at its standard weight doesn't seem right.
It's there (the Unity / Rhythm / Balance... example)!
Lato is the sixth one in the showcase.
Oh, I just noticed it. But it's only the title, the rest is Merriweather.
For me the sixth is all Lato -- the blue block that starts with "Unity"