Connecting 220V mains switches (with on-indicator lights) to 12V COB LED lights in series
It all depends on how you wire the switches.  

I'd guess that the two silver terminals are the actual switch contacts, and the brass terminal is one end of the light.  The other end of the light is probably connected to the center terminal (but that's only a guess...)

If you just use the switch contacts (silver terminals) the LEDs should light at full brightness.  The light included in the switch will not light with only 12 volts, if it is intended to work on 220 V.