Yuu has an ahoge and Haru has a ponytail. I know the haircolor are similar but they don't have the same hairstyle. Althought it indeed need a change of hair color, if you can't just watch the hair and make the difference, it's just that you have eyes problems.
Nakatani didn't change Haru's hair color. The picture you're talking about has a blue lighting that makes Haru's hair look darker and more red, but that's just an effect of the lighting. Haru's canon hair is still orange like in this picture. You can tell because the cover of novel 3 has Haru with orange hair.
^All recent artworks I've seen had a far darker shade than the one from the original hair color. And blue light is supposed to make orange hair look dark brown? And it doesn't affect Sayaka's hair at all? Why was Yuu's hair never affected that way in any of Nakatani's art with shade?
I'm just saying, seems like a course correction to me.
^That is correct, apologies for unclear phrasing. Negom has spent most of her time recently creating what seems like wish-fulfillment self-insert characters and having them get together with precure heroines. I much prefer when she ships two actual precure character together.