I know this hasn't been an easy process for you, @JayBlake.
I recognize how important it is to edit categorized transactions without unmatching them. I'm here to share some insight about this.
Currently, there isn't an integrated way to edit the deposit transactions in QuickBooks Online (QBO) once they're categorized. You'll have to undo or unmatch when you need to change or move a transaction to a different account. We do this to avoid discrepancies when performing your monthly reconciliation.
To avoid falling into this situation again, you'll want to review your transactions first and ensure everything is correct before you categorize and match them.
Feel free to use these articles to help you manage your reconciled transactions:
For future reference, here are some resources to help you fix it in case you encounter some reconciliation discrepancies:
Keep us posted if you have any other concerns or further questions about managing your transactions in QBO. It's always my pleasure to help you out again. Keep safe!