Hi,
Glad you like the site!
In terms of yeast attenuation, we use what the manufacturers list. Attenuation comes down to many factors, including wort profile, gravity, mash temp, fermentation temp, yeast pitch rate, etc, etc...
If we list a number other that what the manufacturer provides, no doubt keen brewers will notice this and ask us to change it back...!
What strains are you specifically concerned about? We could do some more research, maybe add a * next to the attenuation field on certain strains so it is clear the attenuation is a wider range.
You can always change the yeast attenuation by checking the 'custom attenuation' box in the yeast section and entering your own value.