Happy birthday
The song "Happy Birthday" is recognized as the most-recognized song in the English language according to the Guinness World Records.
The Language of the song Dota is Swedish.
Brenda Song speak English and Korean and she is bilingual.
The language used in the song "Out Tongue" by Thriftworks is English.
The song "Gypsy" sang by Shakira is in English and Spanish
The song is in English, but she has a heavy Romanian accent. 
Swedish is the language sung by Basshunter in DoTA.
yes
The entire opera "Madama Butterfly" was written in Italian, and is most commonly performed in that language, although translations into other languages, including English, are also performed.
a song sung in the Swedish language, "Caramelldansen" is "The caramel dance" in English
She speaks English,Chinese,Korean and Vienamese
It seems that most of the people of Earth have decided to learn English as their second or first language. Thus most people on Earth can speak and or understand English. When you make a song for publication, you do so with the intention of making money from it by selling it as widely as possible. Making it in English is therefore the best strategy as this makes it available (understood by) the most people on Earth.