One way you can make sure you don't inadvertently make changes is to use assertions, similar to how you'd use assertions in a programming language. For example, you can enter a balance assertion that's identical to the month-end balance on a paper statement you receive. If you somehow later mess up transactions somewhere so that the assertion becomes invalid, plain text systems will let you know.

BTW, I think one of the main differences between Ledger/hledger and Beancount is whether assertions are interpreted per-file or globally.