Exactly, this is not the correct way to play the polyrhythm. My teacher years ago told me to play it that way and while it is not strictly correct it is unnoticeable to an audience. Do you play the polyrhythm strictly correct?
Well, the notes do not coincide, except for the first of each group (5 or 6), but whether they are strictly correct, I mean whether I hit each note on the correct 30th subdividision of a pulse, I'm not sure, and I don't think that's really what Chopin had in mind for most of his polyrhythms in any case. I'm sure someone has learned those measures strictly mathematically, by breaking up the pulse into 30 subdivisions, calculating where each note in each hand occurs, tapping out that rhythm slowly, increasing the speed, and then finally getting it to feel like a real even six in one hand and an even five in the other, but it does not seem very efficient. The people I know who are naturals at polyrhythms do it the way klavieronin suggested, practice hands separate and then just throw them together. Not everyone can do that, though. I think the main thing is to try for the feeling of freedom and looseness that comes from the notes not lining up strictly. Thorn's suggestion of just alternating the notes after down beat is also good.