As I recall, Kubota themselves only made glass windshields themselves but did contract with another company (I believe it's Curtis) for dealer/manufacturer options, including cabs and windshields.
I'm not sure but from your description, the windshield is probably made of acrylic. You can try but getting scratches completely out of acrylic is a hit-or-miss venture. It may be better to find replacement piece or switch to polycarbonate (commonly known as Lexan).
For removing the scratches, here's what I'd try:
Start with a small area, not in your line of vision.
Using traditional Lemon Pledge (yea, the furniture stuff but don't use a substitute), spray it on, and buff lightly until any streaks are gone. This alone may do it.
If Pledge didn't do it, get some Novis plastic polish. They make different "grits" so make sure you get their product for the most minor scratches. Use as directed. If needed, after that step, try the Pledge over the same area and see what that gets you.