A journal entry can be made for a date that is in a closed bank reconciliation
You can make a journal entry that has a bank account as one of the distributions, to a current or prior accounting period even though the bank statement is reconciled. The journal entries will be on the next bank reconciliation.
For example, the August bank statement is reconciled:
A journal entry made in September dated August was created:
On the next bank reconciliation you will see the journal entry, in this case, it is JE 235: