You asked
Can records be changed or deleted without anyone knowing?
The short answer
No. Every create, edit, and filing is signed and linked into a chain, so every change stays visible and every record is kept.
When a record is replaced, the old version is kept and can be brought back. This closes the door on the kind of quiet alteration that leaves no trace.
One click checks the whole chain and confirms nothing was inserted, removed, or altered, which is what lets a government stand behind its record when someone asks.