I'm not trying to offend anyone, or anything like that, but why can't you say anata or aishiteru or things like that? I'm genuinely curious.
don’t worry no one is going to be offended just because you ask. more like people are going to be offended, because i said it sounds dumb.
basically, they are grammatically correct, but using them in a situation where they do not belong (= talking to your idols) is inappropriate. like, anata is the polite form of you, but it’s supposed to be used when you have ~a deep intimacy~ or something with the person you are talking to. like a wife talking to her husband. if you want to be polite when talking to a japanese person, use their name instead.
aishiteru is —- well it has a lot ~deeper~ meaning than the english ’ love you’. probably because they have ‘suki’ and ‘daisuki’ and those are ok to use when talking to/about your idols. aishiteru is something even your boyfriend would probably never say. unless he’s proposing to you or something.