Yes, I agree. I had to stop using my shampoo “soap” bars after months. My hair started falling out and my scalp had sores all over it. I make my own syndet shampoo bars and have used them for years now. My family loves them.
Actually you can add ACV to a poo bar. I wouldn't have thought it could work either but this lady pulled it off. I have made her recipe and it worked well. I'll include the link if you'de like to review her work...
I have this issue because I live where we have VERY HARD water. You can try adding sodium bicarbonate or borax to your shampoo bars at trace (cp) or after cook (hp). You can also add ACV to your shampoo bars which will help bring them in the pH range that you want for hair products.
Adding more coconut, Palm, tallow, hard butters (shea, cocoa, mango), or even beeswax will give you a harder bar. Have you tried running it through soap calc?
I know this post is probably late but with Willow Bark extract you can use it at any ratio clear up to 100%. All educational material I have read states that it is safe and been tested at those rates with no adverse reactions, unlike synthetic Salicin.
Just thought this might be helpful for...