It is hard to do something common for many at the same time.

Several strings of LEDs to have light if one string fails presents problems in a simple design because from the beginning 3 strings maybe needed ( 3 separated systems).

There is another solution with limited capabilities and it is a single string with a capacitor to limit the current and a group of transistors ( behave like SCR's) to short circuit damaged devices (it does complicates the design a lot).

It is best to insure that the LED's have the limited current stable for maximum life.

3 strings can be made in parallel and fed by a capacitor to avoid having a transformer IF an Integrated circuit is not warranted or desired.

SUPERTEX produces several types of Integrated Circuits specially designed for High Voltage AC driving strings of LED's

So what is the decision ?.