You ask about catastrophic tank failure .....
For over 15 years I had tropical and a marine aquariums untill I had a catastrophic tank failure.
I was woken up one night to a buzzing sound, being half asleep it took a while for me to realise it was the sound of a pump running dry, so down stairs I go, hit the carpet and walk towards the light switch and squish squish under foot, my largest tank had cracked diagonally and dumped the water on to the floor.
The tank was a bespoke made one by my local aquarium supplier it was 1.8m x 600mm x 450mm. It had been in place for over 7 years with no issues.
I emptied one of the kids plastic toy boxes and did very similar to your emergency set up, I lost a few fish but my golden nugget plek survived which was my favourite and he was about 5 years old.
The real issue was the clean up, I hired a carpet cleaner the next day and thoroughly cleaned the carpets, which seemed ok, but within a couple of days the smell was unbelievable, I had to get rid of carpet and underlay very sharpish, my Mrs was doing her nut, I even had to sanitize the floor screed as that stunk as well, the whole house then stunk of jeyes fluid, funny how you can rarely please the wife, I know which smell I preferred and it wasn’t the fishy water one.
I then got a lot smaller tropical tank, but in the back of my mind I had the fear of another disaster, a couple of years later I sold off every thing. That was 7 years ago
I am regularly tempted to get another marine tank, one of my good friends has one and every time we’re there I spend most of it just looking at the fish.