What's an example of wrong syllables?
I imagine OP was referring to the fact that they pronounce virtually all words מלעיל, when in reality most words in לשון הקודש should be pronounced מלרע.
I would add that this is a mistake that much of the litvish community makes as well (likely due to the fact that English is always מלעיל), but maybe it’s not quite as pronounced. It’s sometimes surprising to hear how people who are otherwise very learned can mispronounce important things like קריאת שמע.
I don’t know if it’s an issue in Halacha, as I think I once heard that these things are not problematic if society pronounces them that way (anyone know a מקור for that?), but I find it surprising nonetheless.