​No, because my patch does not change the current behaviour of the code. The assumption that [:alpha:] is OK to use here instead of A-Za-z is already in the code.​

​From the conversation on other bugs, I think that the correct thing to do here is to remove the first part of my patch (so that the hardwired dictionaries keep their individual casechars and not-casechars settings), and keep the second part of the patch (so that ispell-set-spellchecker-params does not change them all to [:alpha:].