First, please use code fences when posting code in the forum
No, just another rule, it can be in the same file as before but I recommend that you separate the rules files according to function. for example: heating.rules, network.rules, presence.rules, lighting.rules…
Have you tried:
rule “light_on”
when
// left switch
Item KAKU_AWST_8802_L changed
then
if (KAKU_AWST_8802_L.state == UNDEF) return; // Do nothing
KAKU_AGDR_3500.sendCommand(KAKU_AWST_8802_L.state)
end