In Mina case she claims that she was abused by Jimin and she went through a lot and that she suffered mentally to the point she wanted to end her life why hasn't she taken any legal actions like people do ? I know you might say that she might have money problem but if i remember correctly she always claimed that she had proof to bake up her claims so eventually she would have been compensated for all the damages.
Seolhyun and Jimin :
Now going to Seolhyun and Jimin case so far all Mina has being doing is running this two girls image the more she speaks the worse it gets for them so according to what we saw so far a lot of Mina claims are fake or exacerbated so it kept wonder why non of Seolhyun or Jimin aren't taking any legal actions for defamation ?
Fnc : Mina also accused Fnc for not doing their job properly and failing to protect her but the staff that worked at the company cape forward to refute this claims.
Tldr : why no one isn't taking any actions to stop this shenanigans ? The longer this keeps going the messier it gets.