The SMD switches change the pinout of the SOP44 socket between MX29L3211 and MX29LV160.
MX29L3211 has A20 where MX29LV160 has WE.
So that pin of the SOP44 socket needs to go either to SNES A21 or SNES WR. So the switch switches it depending on what you want to flash.
Note: It's A21 because we flash in 8bit mode so the flashrom starts at A-1 (A negative 1), while the SNES side starts at A0, so SNES address side is always one more.
MX29L3211 has WE where MX29LV160 has RST.
So that pin of the SOP44 socket needs to go either to SNES WR or SNES Reset.
So that's the other switch's purpose.
Note: In the schematic of the flash adapter pcb WE goes to /IRQ which is wrong and gets fixed by the bodge wire shown here: Flash Adapter · sanni/cartreader Wiki · GitHub
Also there is a second error in the schematic: OE needs to go to SNES CS not SNES CPU Clock.
This is the reason for the second bodge wire.
MX29L3211 SOP44:
MX29LV160 SOP44:
The GND wire next to the switches was just part of the symbol of the switch and represents the 4 legs in each corner that hold the metal case of the switch to the PCB.
Edit: Just for sake of completion here are the other two TL866 adapter pinouts:
AM29F032 TSOP40:
MX29LV320 TSOP48:
