Video Game Logic - Hmm, I get it now.

The Mass Effect one is justified (to a point) in that your armor (and presumably your omnitool) comes equipped with translation hardware/software.

You can read about it here.

Depending on the word it could be something outside of the normal speech and isn't used enough to warrant being in the translator's dictionary, or there isn't an english word for it but can be extrapolated on.
Or they didn't give a shit about consistency.