This is what i get when i selected your options
Altho i think i found the problem, i clicked on supplies when opened the building comparison, then i switched to culture and got no results. Now if i click on culture buildings when opening up, then i actually get the correct results. I dont know about first time, must have been similiar. I think the function can work if you navigate to it correctly, some work should be put into navigation of the site however.
Altho i am again not sure about Garden of Harmony, Temple of ages and other top buildings, they dont seem to be from chapter I or II. But now i read that you did say that it shows from chapters 1-5, so i guess there are some bugs, but the tool could be used if youre smart enough to work around them.