How to Control Lights with Domoticz, MySensors & Radio Switches Without Server Dependency

Hi.
I have an existing electrical installation in my house, unfortunately not very functional. I would like, without interfering with the cables, to do radio control of two chandeliers independently from two or three locations. I have two such cases at home. The third is the switching of lights on the stairs - two switches also radio-controlled.
I was tentatively thinking of permanently short-circuiting the wires in the boxes to get the power supply to the chandelier, and in the chandelier a radio receiver with a relay to switch on the bulbs. In turn, surface-mounted switches will be stuck on the walls.
In addition, I want to monitor the temperature and humidity of several rooms and add other monitoring points over time. Hence the idea of Domoticz using the MySensors system (Arduino nodes + RFM69, control panel on Raspberry PI). However, I don't want a situation where a server failure paralyses my lighting control. I would like to be able to control the lighting locally from the radio switches, and if the server is available, control from the network and read out the status.

Can anyone direct me to a solution to this problem?

By the way a question, does anyone know where to buy such a switch without electronics:
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Alternatively I will use this Chinese solution Link , along with the receiver, at the chandelier I will add a second radio coupled to the Domoticz. The question is how much is this Chinese radio worth?

Without interfering with the cables it's going to be difficult to make a universal control fail-safe for the central unit. I suspect you don't have a neutral at the switches and this is the main problem. Otherwise you could control with, for example, Sonoff switches with the soft changed to Tasmota or EspEasy. In my opinion, control via wifi is more stable, and even if your Domoticz server goes down you can continue to control via wifi via a browser.
In the future, if someone wants to modernise the electrical network, it is worth making all the switches as staircase switches and supplying neutral to them.

WiFi is not the solution here. It eats up that 0.5-1W, and I still don't have a simple and quick way to turn on the light. Although I confirm the stability of the ESP8266 - it's surprisingly good for its price.
The solution for me is wall switches sending commands directly to the module in the chandelier, and this module has the ability to communicate with Domoticz too using the same radio transceiver of course.

As you write the lighting can be done very cheaply on a Chinese 433Mhz radio and for this a sonoff bridge. I'm not sure but I think it can be integrated with Domoticz. The only thing I don't like about this radio is the one-way communication, no information about the lighting status.
Anyway, there are gateways on mysensors, solutions for every communication standard.