The trick with these rhythms is to focus on notes of the left and right hand that should be played on the same moment.
For example in Fantasie Imp. its the first note of every set of 4 16th (right hand), with the first note of every set of triplets in the left hand. So the Fx of the right hand comes on the same moment of the E (first note of second triplet) of the left hand.
To get those notes in between right, is pretty much matter of playing those rthythms together alot, and focussing on getting them fluently towards the notes that have the same timing.
good luck,
Gyzzzmo