There are people who have done damage to headlight housings with 55W bulbs, and shitty LED's. So while it might not have happened to fog light housings, it is a risk you are running.
35W kits are already so bright, 55W for an extra little bit of light and extra risk just doesn't seem worth it.
And yes, various Toyota and Audi/VW forums have plenty of posts about damaged fog light housings due to 55W HID's.