473 has a defined format, so including generic text in the event header is redundant. You could put a specific channel in the header if you want, or leave it as a wildcard and inside the event check that $2 is a channel you have a defined invite command for. Since you know these channels are invite only, maybe you even want to ignore the message using haltdef.
raw 473:*#chan1*:invite_cmd_1
raw 473:*:{
if ($2 == #chan1) { invite_cmd_1 }
elseif ($2 == #chan2) { invite_cmd_2 }
}