just a guess, but if you change this section (about line 962 in Notepad++) of the unitframes (high or low, depending on resolution) in ..\World of Warcraft\Interface\AddOns\Tukui\unitframes
folder (i.e - unitframes.high.lua)
Code:
self.Buffs = CreateFrame("Frame", nil, self)
self.Buffs:SetHeight(26)
self.Buffs:SetWidth(252)
self.Buffs.size = 26
self.Buffs.spacing = 2
self.Buffs.num = 9
self.Buffs.numBuffs = 9
to whatever number of buff you want to show (for example)
Code:
self.Buffs.num = 18
self.Buffs.numBuffs = 18