Is this tank setup okay for morphs?

[kellsnotokay52]

The picture of the tank below is what I made for them after the four newts died. They are fire belly newts.
The water temp is 63f
About 2 inches deep
Land area.

I've had 4 die today out of 60. Confused why they died. Could they have drowned? They do come up for air sometimes. In the old tank there was about 6 inches of water and no land but a lot of plants. Will they still go on land even if they have gills?

 

[Bellabelloo]

It looks good to me. I would however have some place they can hide on land for when the do fully morph. I have noticed that when I have any morph, they do spend some time with their heads out of water while the gills are still there. I am a little paranoid about them drowning during this stage so I use less water.
Do you have a secure lid on those containers? Once these little guys start morphing, they are spectacularly good at climbing.