It is even simpler ...
the CE marking on such product is misleading and stands for China export
the circuit uses no power switch so it has to be open when the LED is not connected and since it is not going to be used for long time, so temp. coefficient is not an issue, the Chinese will use a Basic CCR circuit with 2 transistor 2 cent each and 2 resistor with a cheap 6LR61 9V battery as it will be active for several seconds, the main cost will be in the enclosure.
attached is the ISIS expected circuit for the 1mA CCR and you can alter the fixed resistor for other currents.