good to ask here, to get the more theoretical viewpoint.
But i am sure you have asked here aswell..
https://www.electriciansforums.net/The radiator doesnt need to be earthed, but it wont be harmful to do so.
Unless you can draw a schem of some danger situation with your earthing method, then its fine.
I cant see any possible danger of any of the situations you have described.
I presume you have an RCD in that part of the wiring that goes back to the earth/neutral junction?
Even with a wiring system thats not earthed, and use of severely dangerous kit, it can be hard to shock yourself...as you see here at 7:30
Here is the first part of this
However, i absolutely recomend not doing this and only using electricians standards in wiring.
Millions of households in Brazil for example, dont have any earth connection or any earth wiring, and there are few if any reports of accidents.