I spoke Spanish and German interchangeably. Is it correct to say, “I snapped on the Spanish part”?

The phrase "I snapped on the Spanish part" might not convey your intended meaning clearly. If you're trying to express that you started speaking in Spanish or switched to speaking Spanish, you might say: - "I switched to the Spanish part." - "I started speaking in Spanish." - "I switched to Spanish." The term "snapped" can imply a sudden or abrupt action, so it may not be the best choice in this context unless you're trying to emphasize a sudden change in your language use.