Pushmode uses a slower queuing system and thus the bot will have time to stack multiple mode changes into a single line, meaning you should see less lines with mode changes if a invite flood would actually occur.
Same goes with putkick that will combine multiple kicks into a single line with the same reason, but while it sends a single line the server still shows you multiple kicks lines in the chat. Nothing we can do about it I'm afraid.
In order to actually have something stacked you would have to delay the punishment in the hopes there's a invite flood before triggering the actual punishment, just like it happens in the script you linked.
Since you have the linked script already loaded, reusing the stack_bans function is the last of my concerns. In my honest opinion you would just complicate things because then you would also have to keep track of name changes inside the array with names to be kicked off any channels that the bot and the victim have in common thus need to add nick, kick, part and quit functions.
Honestly I would rather wait for an actual invite flood and see how this behaves and take it from there.