Please help me identify this LED from a Nuevo (HGH0242) / Horizon Lighting 5-pendant light fixture
You need to find a COB LED (Chip on board Led), 350 mA, with a voltage range of 10-18 Vdc, more or less 5W. More or less 600 lm.
The number of lumens can be very different, it's just an estimate for 120lm/W. It can be as low as 300lm. But it helps narrow the search.
The voltage of the LED is equal to the voltage of the power supply divided by the number of LEDs in series. (Check if there are really in series). It's important that it matches the voltage range. The voltage range can be more or less 2V for the lower and the upper limit and can be narrower than what I wrote.
For example I found this one and this one.
You can go to other vendors as long as the parameters are respected.