I would appreciate your advice.
If an artist gives his idea of a song to a person in a foreign language and then asks someone to write the song in English (because his command of English is not excellent), then the lyrics are written, not a word for word translation but sticking to the genre of the foreign text. Then this English version is the actual released song and is a hit.
What royalty rights does this person have. Is he seen as a co-author? Also, if someone gives a song idea but wants the lyrics "cleaned" up so to speak for it to read correctly, to flow better by using another word etc…are royalty rights also given to this co-author?
Your questions are excellent. The answers, however, are not cut and dried.
The percentages of ownership in a copyright (aka "song") totally depend on the "agreement" made between or among the participants. That's why I recommend highly in my book, "How to Get Somewhere in the Music Business from Nowhere with Nothing," that at the moment a song is "fixed" on paper or on a recording, the writers (or anyone involved in the song) should come to an agreement about shares of ownership. Then they should write those points down in a "letter of agreement," that everyone involved signs (no photocopies). Each writer should get a copy with an original signature. ( I have a template for a simple letter of agreement in the back of my book)
It all depends on how crucial or important the contribution each person makes. A GREAT idea can be the genius behind the song and may deserve more than a simple "nod of acknowledgement." The same is true for a great "riff" or an identifying instrumental or lyrical idea that "makes the song." On the other hand, if the person's input was minimal, it should perhaps not deserve as great a percentage as those who actually created the words and melody.
Remember, there are four component to a song: LYRICS, MELODY, HARMONY, RHYTHM. The two "non-negotiables" are the Lyrics and the Melody. They comprise the "copyright" of the song. The rhythm and harmony can be changed by various producers or arrangers to suit various styles of recording artists. But the copyright belongs to those who wrote the lyrics and the melody.
The above guidelines also apply to someone who wants their lyrics "cleaned up." How much "cleanup" is involved? How great is the idea behind the song? You can "slice the pie" as thinly as you wish -- in terms of ownership. It's all up to whoever writes the song.
Hope this is of help.Don't hesitate to let me know if you have further questions.
All the Best,