Tbh the only thing am not going fault them on is them saying they aren't or are trying not to curse around the kids, my grandparents an great aunt never cursed so both my dad an uncle don't as obviously not hearing it from their parents or aunt meant it just didn't become a thing, me on the other hand is a totally different story because my mum an her side all have a hell of a mouth on them
But I do try as well as my brother not to curse around my neice an that stems from when I took my little cousin out when she was young (maybe 4) an every second word was fk, an am not going lie it was actually quite mortifying hearing it, the odd curse word sure am going brush it off but when young kids release a word is "naughty" it's like an addiction, they just won't shut up with it an having a young kid belt out fk every 3 seconds in the middle of a crowded mall was just not as funny as you'd think it would be, plus school as well was definitely not happy about it an unfortunately for my cousin it meant being unfairly punished for a word that wasn't her fault but because her parents just kept allowing it
So I do get if they don't want to curse around the kids, it isn't a kids fault with cursing but unfortunately it's the kid that gets the punishment for it in school or clubs from teachers/mentors