It is untrue that the Rosetta Stone actually has three languages, it does indeed have two - ancient Greek and Egyptian. However, the Egyptian text is written twice but in different scripts: Hieroglyphs suitable for issuing a priestly decree, and Demotic which was the cursive script used by ordinary people for daily purposes.
The away team visit what is supposed to be the planetary core of a gas giant after its atmosphere was "burnt away". However, about 90% of such an atmosphere is made up of helium (which doesn't burn) plus hydrogen (to make water vapor) which has the effect of greatly increasing the mass (and therefore gravity) of the gas giant.