Adding LingQs and change the rating of how well you know a LingQ or marking a LingQ as known will give you coins (more for learning LingQs)
I don’t believe words read or time spent listening has any affect on coin count.
Because your Learned LingQs aren’t at the suggested goal markers that would be why you have trouble hitting your coin goal. I think marking a LingQ as known is worth 4 or 5 Coins.
That is how I understand it anyway.