when your mounts get weak, they engine moves around alot moe than normal, that explains why your "jaalis" keep dying. the 1st silencer walla was clearly an idiot and you should make him pay you back for all the added headaches you've had so far.
my accords jalli went years ago, i just went and bought a new one,... never gae issues again.
in pakistan people will pay 500rs 10 times to get the same problems fixed again and again, rather than 5000 once,.. never made sense to me.
BTW to correct way to check if the part with water would be to fill it with PRESSURIZED WATER not water under atmospheric pressure so thechnically the mechanic didn't do anything spectacular except a little bit of "magic" to impress you.