Exactly, just because a program is compiled to target a 32bit CPU architecture, that doesn't mean it can't still use 64bit numbers internally. Cobra is a 64bit engine that in the current releases is compiled as a 32bit application.
Why 64bit numbers are important is precision of location.
Floating point numbers are interesting in that the magnitude of the number is not limited, but the precision reduces as the magnitude increases. What this means for a space game is that if the Sun were 0,0 on a 32bit coordinate system you might get meter level accuracy at Mercury, accuracy to within ten meters at Earth and accuracy to within a kilometer at Pluto.
The gameplay implication of that would be that dogfighting around Pluto would become impossible. Ships would jump around from one kilometer level accuracy point to another.
Using 64bit accuracy for the coordinate system doubles the accuracy of numbers that can be stored 32 more times. That means that precise coordinates can be stored over a range of about a light year.
The distances and accuracies here are suggestive, the actual figures will depend on the implementation inside the engine.
Thanks; Crayfish.