Yee I agree, It'd be cool to see death dialogue & game overs in the "Play Test" sections of the Ghostiary.
I do have a couple solutions to access Game Overs easier, tho they both involve going into the game's files
1. Go to resources > enemy and edit an enemy's code to make them appear more frequently. The code is plain text files so you can edit it pretty easily with smth like Notepad. The specific string of code is usually pretty close to the top of the page; you can change the enemy's "appearances" (which floors they naturally spawn in) & "chances" (how frequently they appear for each floor)
2. Go to resources > sprites and simply view the raw image files used for Game Over screens. There's no background or text but its the easiest way to view them aside from maybe looking up a compilation on YouTube