Basic answer is yes, you do get into trouble.

All overnight accommodation and long distance travel within China needs to be registered against your ID. It's pretty much transparent for hotels, trains, planes, but when renting private accommodation you need to ensure that your host is doing it for you. If not you need to do it yourself and that's complicated as you usually need paperwork relating to the accommodation.

The consequence is not likely to be immediate but you may get asked awkward questions upon exit if it's noticed that you have incomplete overnight accommodation or long distance travel records. But more likely is that the next time you attempt to enter China you will get a lot of questions and maybe denied entry depending on the circumstances.

And in case you think this is a special policy for foreigners, it's not, you're getting equal treatment as the locals.