That only works up to a point. If the character looks too young or certain aspects aren't something you'd really ever see if they are of age (ex. they're not potty trained yet, they still need a babysitter, the school still has nap time and/or recess, the parents are barely over 18 themselves), they will just go "Yeah, no. There's no way she's 18 or older." The operative word is "questionable". I highly doubt you'd be able to successfully argue Tiffany as she is now is 18 or older.
Yes, it is. Anyone who blames you is ignorant of the difficulties faced by devs with loli characters (I'm not one, but I can understand it). If anything, I blame the people who have nothing better to do with their time than scouring the internet and being a White Knight toward fictional characters. People who likely have trouble differentiating between reality and fiction because they think "harm" is being done.
That said, I will still follow the game. The lolis were a plus, but they weren't the only reason I played it. There are plenty of games with them that I dropped because the story and/or other content didn't interest me. This was not one of those.