I'm sorry, I posted that late at night. You'd probably find it useful to know that I am running kernel 4.14.0-kali-amd64 on the Lenovo. The processor is an AMD A12-9720P.

Thank you for your interest in Kali, but we are not able to deal with such hardware support problems. Please read https://kali.training/chapter-6/filing-a-good-bug-report/ first.

And consider that we are not kernel developers, if you know of a fix, we will gladly integrate it in our kernel build. Otherwise your best bet is to wait the next kernel update and keep around an old kernel that works for you (for example by installing an old known-working Kali image).

Given that the touchpad works just fine under Windows, it doesn't really seem to be a hardware issue so much as one of faulty drivers. Which would seem to be a software issue, and not one involving the kernel.
But what do I know? Thanks for your time.

Most drivers are in the kernel. But even if the problem is at the Xorg level, it doesn't change much, this is not an issue that we can tackle on our own at the Kali level.