I do not consider any of these Chopin polyrhythms as something that needs to be palyed mathematically correct. Rather, the figure should be played freely over the left hand, which should remain steady. Basically, sync the beat starting the right and left hand figures together, and then the right hand is basically playing freely, with no note synced together with the left hand until the first beat in the next bar.
You can practice it by playing the right hand first three notes as a triplet and then normal 8th notes, and then the other way around; first four normal eight notes and the final three as a triplet. Then finally, start desyncing the "beats" you have practiced in the right hand from the left hand and try a couple of hybrid versions of the two practice models until you can play the figure freely over the left hand.