To be correct; the latest Keynote is version 6.1 not 13.
Slide transitions are not builds, they are a separate type of effect. Only Builds appear in the Builds Order List. Builds are effects for objects, transitions are effects for slides.
The effects you want can easily be achieved however;
to add the build to the object on the slide:
click the object on the slide to select, Inspector > Animate > Build Out > Add an effect
to add a transition for the slide:
click the slide in the Navigator pane to select, Inspector > Animate > Add an effect >
select a transition effect
to action the transition after the build:
in the Start Transition dropdown menu, seect Automatically