the 7/8/SE (2nd gen) home buttons are not mechanical, like those in the 4/5/6/6s, and really don't have a "sensitivity" that can be adjusted. that said, i have found that loosening or tightening the screw that holds the actual button to the home button display bracket can change how the button responds to a touch.
on a side note, did you DIY the Turtle IC replacement? if not, can you tell me who did it, if it's a commercial service with a website?
also, did replacing the Turtle IC make the Touch ID stop working? or is the home-button-to-motherboard pairing for Touch ID not rely on the Turtle IC chip?