There are several issues at play here, native keybindings for input fields has not being fully implemented in servo yet.

As of auto complete, few people have reported issues. In our testing we did not run into this issue. Right now we have an issue and a reproducible test case to tackle this issue: https://github.com/browserhtml/browserhtml/issues/1157

Feel flee to report more browser.html issues here: https://github.com/browserhtml/browserhtml

We'll do our best to get them resolved promptly.