As the topic said the API func API_GetColouredName only works for single colour.
If the user has a gradient colour the api return the #5af hex code.
Can u please fix this?

This is intended really, I may add a GetGradientName in the future. Issue being gradient names would return the full name not just one color as mostly each character has a seperate one, which would be quite confusing in that existing api method.