Where Can I Get Information on kintone Such as Maintenances and Failures?

The information on maintenances, failures, or updates is provided on Notices distributed from Cybozu page.
You also can check the status of your service environment on cybozu.com Status Dashboard page.

Additionally, you can check it on the following page in your product:

When you click the i icon in the header in cybozu.com, notices appear.
A number next to the icon indicates the number of unread notices, if any. Top of cybozu.com