I don't know if you're using Quicken for Mac or Windows. In Quicken for Mac, if you realize you accidentally deleted a transaction, you can just Undo (Command-Z) and the transaction will be restored. And Quicken has multiple undo, so you can back up and undeleted multiple actions if you need to go back several steps. I originally asked for a confirmation message when I started testing Quicken 2015 after many years with Quicken 2007 and earlier, but in practice, I've found the unlimited undo functionality is better than having to confirm every deletion.. (You may not agree; I'm just offering my two cents...)
This requested feature was added in version 5.12 in August 2019.