I translated 'producers' with 'Produzenten'. even though I agree that 'Hersteller' would be a better choice – can't these words mean the same (e.g. film producers) and should hence both be considered a valid translation here?
Both are valid. Please report it.
Why not this: Welcher Hersteller würde diese Beschreibung veröffentlicht haben?
Because “Which producers…would have…” is plural, whereas ‘Welcher Hersteller würde…haben’ is singular.