No need to worry about the L vs. N connection.
No specific orientation, just ensure the AC 240V connected to the input of the step down transformer.
Refer to this post for further details.

If you compare the doorbell owned by psyntium vs. sw.boutique, the two are entirely different design.
However, the doorbell with two wires design still backward compatible with existing wiring (4 wires type).
It's just a matter of connections. For further assist, post the picture of the doorbell.

Here you go...
Conversion from 4-wires type to 2-wires type doorbell.
No major modification needed. Just add one terminal block connector.



Please take note of this type of doorbell design weakness!
If your doorbell switch located at outdoor and exposed to rain water, make sure you use the outdoor rated switch.
Non-outdoor rated switch will give you headache due to short circuit caused by water.
Short circuit will lead to nuisance MCB tripping.

Yup, warning already given about the potential short circuit hazard!
That's the reason why there's a another variant design with step-down transformer.

Pros and cons...

Transformerless: Simple, reliable and low-cost. Suitable for indoor application like apartment.
Step-down transformer: Safer due to transformer isolation. However, the system always on standby mode and consume electricity.

I found this outdoor enclosure box for doorbell switch at lelong.com.my.
If you really like it, just go ahead install your doorbell. Ensure proper weather sealing for the switch.

You can't add step-down transformer to a doorbell system that required AC 240V as input power source.
Just buy the weatherproof switch to solve your problem.

Since you like and desperate for that doorbell.
Here you go...



Referring to above schematic:
● The doorbell switching done by AC relay.
● Relay energized by step-down transformer power supply.
● Outdoor switch running on low AC voltage.

Relay need power supply to energize the magnetic coil.
I think the transformer and relay can be fit into the casing.

Could you remove the small black plastic cover and provide me the picture of the circuit?
If you refer to first post (two-wires type) by TS, you can see the circuit of the unit.
I have another idea to modify the circuit to let the switch run on low voltage.