I am slightly confused by this. Is AIRLINER_LIGHTS_EXT_STROBE an Input Event? If so, you can just assign directly to that, or in lua you can use the ipc.execInputEvent function. You can it it to an offset if you like, and can then write to that offset to trigger the input event using one of the ipc.writeXX functioons. But you cannot add it to offset 65590 - that is outside the range of available offsets. Choose one in an offset area that is free for general use, such as 0xA000, e.g. to add as a byte value (for 1/0 or on/off values, or numbers in range 0 to 255 or -125 to +125) it would be:
[InputEventOffsets.Default]
0=AIRLINER_LIGHTS_EXT_STROBE=UB0xA000
You can then assign to Offset Byte Setbits or Togglebits, and in lua you would use ipc.writeUB.
But you only need to add it to an offset if you need to read the value for some reason.
This doesn't makes sense and gives that error you see, This sends the FS control with number 65590. There is no such control with this number hence the error. Do not confuse control numbers with offsets - they are completely different things.
Please also note that these forums are now closed. Please use the new support forums, available here: https://fsuipc.com/support/
John