[SDPhantom]

This is what I've come up with. I ended up rewriting it from scratch while using the newer version's position calculation as it was cleaner and I had already made it configurable.

--  Config Constants
local Aura_Size=21;
local Aura_Spacing=2;
local Aura_ShortCols=4;--   Buffs per short row
local Aura_ShortRows=2;--   Number of shortened rows
local Aura_NormalCols=6;--  Buffs per remaining rows
 
--  Calculated Constants
local Aura_ShortPadCols=Aura_NormalCols-Aura_ShortCols;
local Aura_GridSize=Aura_Size+Aura_Spacing;
 
local function ReanchorAuras(self,auratype,container,prevrows)
    prevrows=prevrows or 0;
    local nameformat=("%s%s%%d"):format(self:GetName(),auratype);
 
    local point,relframe,relpoint,offsetx,offsety;
    local rowcount,lastrowanchor=prevrows,nil;
    for i=1,math.huge do--  Trick into running an infinite counter loop
        local auraframe=_G[nameformat:format(i)];
        if not (auraframe and auraframe:IsShown()) then return rowcount,lastrowanchor; end--    We're done, return here
 
        if i>1 then
            local posindex=i-1; if not self.buffsOnTop and prevrows<Aura_ShortRows then
                posindex=posindex+math.min(math.floor(posindex/Aura_ShortCols),Aura_ShortRows-prevrows)*Aura_ShortPadCols;
            end
 
            local x,y=posindex%Aura_NormalCols,math.floor(posindex/Aura_NormalCols);
            auraframe:SetPoint(point,relframe,relpoint
                ,x*Aura_GridSize+offsetx
                ,(self.buffsOnTop and 1 or -1)*y*Aura_GridSize+offsety
            );
 
            if x==0 then
                rowcount,lastrowanchor=prevrows+y+1,auraframe;
                container:SetPoint(relpoint,auraframe,relpoint,0,self.buffsOnTop and 1 or -1);
            end
        else point,relframe,relpoint,offsetx,offsety=auraframe:GetPoint(1); end
 
--      Note: DebuffType border scales with size, but Stealable border doesn't
        auraframe:SetSize(Aura_Size,Aura_Size);
        local stealborder=_G[nameformat:format(i).."Stealable"]; if stealborder then
            local size=math.floor(Aura_Size*8/7);
            stealborder:SetSize(size,size);
        end
    end
end
 
hooksecurefunc("TargetFrame_UpdateAuras",function(self)
    local rowcount,anchor1,anchor2=0,nil,nil;
 
    if UnitIsFriend("player",self.unit) then
        rowcount,anchor1=ReanchorAuras(self,"Buff",self.buffs,rowcount);
        rowcount,anchor2=ReanchorAuras(self,"Debuff",self.debuffs,rowcount);
    else
        rowcount,anchor1=ReanchorAuras(self,"Debuff",self.debuffs,rowcount);
        rowcount,anchor2=ReanchorAuras(self,"Buff",self.buffs,rowcount);
    end
 
    self.auraRows=rowcount;
    self.spellbarAnchor=anchor1 or anchor2;
end);