Extract insertions that failed because of size limit from SQL Server Express Transaction Log

I have a SQL Server Express database with Full Recovery Model. Several months ago, the database hit it’s size limit (10GB) and some data did not successfully get added to the database. Several weeks after that point, the database began receiving monthly full backups, but never any transaction log backups. The transaction log is still an overly sized file (>200GB). Both files are free to grow without limit.

Is it possible that this transaction log will contain the data that failed to be inserted several months ago, or is the file just that big because of no truncation/shrinking?

I appreciate that monthly backups don’t make any sense with a Full Recovery Model. That was just the as-found condition.