What is Einsteins E=MC^2 formula in different languages?

I used spanish as an example in your question which I typed in as you wrote it:

“Einstein’s famous formula, (E=mc^2), remains the same in Spanish. The mathematical expression doesn’t change, but the explanation and terminology around it are in Spanish. For example, “energy” is “energía,” “mass” is “masa,” and “speed of light” is “velocidad de la luz”.”

It is the same in all languages. It is a formula. All languages have words that would equate to the meaning of the symbols used. It is a formula. It’s like asking what 2 + 2 = 4 is in a different language.

Having E stand for energy and M for mass is convenient for countries that share our alphabet and have a word for energy starting with e and a term for mass starting with m. The reason for c standing for the speed of light is not immediately apparebt. See, for example, here