There note here is of course that a resistor will not isolate. It will only limit currents.

But a limited current that is allowed to charge a capacitor can allow the capacitor to later produce a very nasty jolt.

So any design that has a resistive connection to mains should be treated as hot. Every single part of a design that isn't isolated from mains must be well isolated to protect people and animals.

And it also requires that the designer is well aware that any testing is dangerous. Having mains to the processor also means that you can't safely connect the processor to a PC for upgrading the firmware.

Because of the disadvantages, I would definitely recommend a switch to a better design that isolates the processor and as large part of the circuit as possible from mains. This could allow the only hot part of the PCB to be separately isolated, allowing you to perform measurements, software updates etc without danger.