Nah if you only build a 2D structure, you won’t have to worry about the water pressure because your structure will likely not be able to interact with 3D matter. It’s genius engineering IMHO.

Sounds like CRTs do produce some radiation but the amount it produces is marginal. Modern CRTs should have leaded glass which should substantially reduce the amount of X-rays you would receive.

https://oer.unimed.edu.ng/OTHER OER VARIETIES/5/1/Ife-Adediran-O-O-Arogunjo-A-M--EXPOSURE-RATE-ASSESSMENT-FROM-SELECTED-CATHODE-RAY-TUBE-DEVICES.pdf

The above article says 0.3 microS/hour which is less than one tenth of the radiation you get from an hour of flight, or about 10 hours of sun exposure.

https://en.m.wikipedia.org/wiki/Flight-time_equivalent_dose#Radiological_exposures_and_limits

So it looks like you will get radiation exposure from CRTs but it is not much higher than background radiation. Bring sedentary for hours in front of a CRT TV is probably worse for you than the radiation you would get from the CRT.