Une précision: la couleur heather elle-même est en effet la couleur décrite par égueule; ceci dit, a heather/heathered colormeans a blended color, subtly combined throughout the strands of yarn. A marl/marled yarn gives a similar effect, but the tone is usually achieved using solid strands of different colors plied together (jaspé, selon le GDT...?)
I think heather/heathered is a good translation of chiné.
Flecked is less subtle than heathered, I think; it might have been suitable for the specific item you were describing at the time.
Here are examples to show the difference as I perceive it:
This tweed yarn is flecked: it has distinct flecks of color.
Here is a heathered yarn. It contains many colors, but the differences are subtle. Marled yarns contain different colored strands twisted together.