Most of anime gaf has correctly guess the female Titan and by correlation has also guessed the armored Titan
Then maybe those things are just that easy to guess in this story. You can say that the blonde hair on both titan and human characters helps the connection, but in manga if you have light/inkless hair then it's most likely blonde as well. They mimic'd a lot of the key shots of her from the manga pretty closely, like when she is crouching and smirking at Armin. The key difference is the fact that the show has many frames in one shot. The manga can hide things better because the artist can choose the exact second where her face is covered by swinging bangs and draw that. The anime can't really do that...
Anyways, I don't think it can be helped. It's not hard to guess in either.