Well, let's use some examples from Star Control II.
- The Slylandro call their homeworld "Source".
- The Spathi call their homeworld "Spathiwa". If I were to hazard a guess, I would think that that translates to something like "Home of the Spathi". If you assume that "Spathi" means people, then "Spathiwa" would mean "Home of the People".
- The Syreen call their original homeworld "Syra". I can't say much about this because it's unclear whether the race name is based on the planet name or the other way around. Their new homeworld, however, is called "Gaia", fitting the common pattern.
- The Supox call their homeworld "Vlik", meaning "Perfectly Good and Nutritious Dirt"; so this fits the common pattern.
- The Shofixti call their homeworld "Kyabetsu". It's impossible to determine if this fits the common pattern since it's never said what it means.
- The Utwig call their homeworld "Fahz". There's a good chance that this means "Earth", but again it's impossible to be certain.
- The Dnyarri called their homeworld "Glilandy" (unless this was a lie). That probably means "Earth", though etymological analysis isn't technically valid here.
- The Ariloulaleelay call their homeworld Falayalaralfali. This could mean almost anything.
So of the races who name their homeworld in the game, only three definitely fit the pattern (including humans). Another three likely fit the pattern. One fits the pattern "Our Home", and another may also fit this pattern. One fits a somewhat unique pattern, "Source", and the final one (Arilou) is an enigma.
So, no, definitely not a 100% chance of calling a homeworld "Earth" in one's own language. Calling it "Source" or "Homeworld" is also logical.