Putting a soft cap at 50% create another rule and will add complexity.
The problem is not in the stat but rather in the way it increases. If you raise your stat with a fix amount, you will go to 100% very fast.
Here is my idea:
Each time she uses a skills, the girl has a chance to improve it. You cast a 100 dice and you subtract the current skill level to this number. The girl increases this skill only if the result is
positive. Above a given level she can even get 2 or 3 points.
When the skill is low, you have almost 100% chance to improve it quickly. When it's high, the progress are much slower, like in reality.
If you use the training, the trainer skills are used: the best the trainer is, the faster the progresses.
We can also imagine that the skills that have not been used for a while will decrease. If you don't practice, you forget: like in reality. We can add events that lower skills like scars.