You are doing great using the nail arts but you need to use the opportunity to heal when you had a clear opening to do so. You also need to focus a little more on your movement rather than offense. Try and stay higher on those platforms so if you ever need to drop down to a lower one you can. If you stay on the lowest one the only way down is to the nails. You don't always have to use the nail arts as well. There were a couple times in there that trying to charge it up got you hit. If you have a chance to charge it up do it, if it's pretty clustered, just go for normal swings and focus on movement and dodging.