I am gladfully surprised. So you have the data! You have tested or made the numbers before implementing. That is great.
I have searched for FT>20, JS<=5 in the transfer list. The numbers are compatible with what you say.
I still think that my approach would be more consistent with the name "free throw" skill, and it wouldn't nerf an already not very important skill.
But I feel more confident in you and your team now.