I can’t answer your origional question, but here are a few other ways to do those exercises.
For glute-ham raise: load a barbell with heavy weight and secure it in place so it doesn’t roll around, you’ll find that the bar loaded with olympic plates is a good height off the ground so you can fix your legs under it, place some old cushions or padding under your knees and under the bar where you place your legs so that it doesn’t cut into the back of them.
This is how I do glute-hams and it’s MUCH tougher than using a machine. Although you’ll need your own barbell at home, as I doubt you’ll be allowed do this at a gym.
For reverse hypers I simply use an old table raised on a pallet, use a dumbell between your feet for resistance.
These may not be ideal for you, but hopefully you can try them before commiting to building your own.
I find GHR excellent for strengthening the hams at the knee to help prevent injury at the end of the swing phase. And back hypers are a safe and very effective way of developing the hams at the hip and also whole posterior chain including outer knee flexion range.
I use the GHR bar method similar to Major described but fixed inbetween a door frame, wouldnt be without it. For the back hyper I bought my own since gyms now seem to only have the angled version which isnt as effective.
The GHR certainly takes a little while to get used to it, like many things just building up gradually helps. I actually get no tendon trouble with it but at first soreness did take a few weeks to get conditioned against.
Moving the strength profile towards the knee or strengthening knee flexion has little (no) benefit in sprinting or in most sports I am familiar with apart from a performance point fo view.