NOT APPLICABLE TO THOSE THAT MAKE A FEW!!!!
NOT APPLICABLE TO AMATEURS !!!!
NOT APPLICABLE TO HOBBYISTS !!!!
NOT APPLICABLE TO THE QUALITY CONSCIOUS !!!!

a cheap lamp dimmer where one in 1000 may fail every year
then a capacitor will be enough surge protection.
Then resistor sense (no opto etc0 will be fine

going to be produced in thousands
NOTgoing to be approved by whatever electric code your country has
you STILL have to make something that does not cause fire or electrocution of the customer (your safety is your problem).

So, In the above case I would make something that, if it fails, will either turn the lamp off (no trigger) or turn the lamp fully on (shorting) and will, in no case cause fire. This brings us back to copying the NXP appnote and INSIDE THE BOX adding a small, cheap, switching power supply (maybe just a resistor, a capacitor and a zener)

Yes, this will make cheap SAFE crap, but, as you say a cheap lamp dimmer where one in 1000 may fail every year that sounds about right.

DO ONE THING
put a 1:1 mains isolating transformer between the mains and the testbench to float the ground, that whay you need to touch two, not one, points to get electrocuted. it does not make it safe, but it makes it safer.

Erik