check
Check for various kinds of errors in your data. experimental

_FLAGS

hledger provides a number of built-in error checks to help prevent
problems in your data. Some of these are run automatically; or, you can
use this check command to run them on demand, with no output and a zero
exit code if all is well. Some examples:

hledger check      # basic checks
hledger check -s   # basic + strict checks
hledger check ordereddates uniqueleafnames  # basic + specified checks

Here are the checks currently available:

Basic checks

These are always run by this command and other commands:

-   parseable - data files are well-formed and can be successfully
    parsed

-   autobalanced - all transactions are balanced, inferring missing
    amounts where necessary, and possibly converting commodities using
    transaction prices or automatically-inferred transaction prices

-   assertions - all balance assertions in the journal are passing.
    (This check can be disabled with -I/--ignore-assertions.)

Strict checks

These are always run by this and other commands when -s/--strict is used
(strict mode):

-   accounts - all account names used by transactions have been declared

-   commodities - all commodity symbols used have been declared

Other checks

These checks can be run by specifying their names as arguments to the
check command:

-   ordereddates - transactions are ordered by date (similar to the old
    check-dates command)

-   uniqueleafnames - all account leaf names are unique (similar to the
    old check-dupes command)

Add-on checks

Some checks are not yet integrated with this command, but are available
as add-on commands in
https://github.com/simonmichael/hledger/tree/master/bin:

-   hledger-check-tagfiles - all tag values containing / (a forward
    slash) exist as file paths

-   hledger-check-fancyassertions - more complex balance assertions are
    passing

You could make your own similar scripts to perform custom checks;
Cookbook -> Scripting may be helpful.