[Fizzlemizz]

It looks like you're wanting something like the following to create a set of columns/rows:

local function buttonFrameButtonLayout()
    local lastRelative, lastOnTop = NewbDevBoxButtonFrameReloadButton, NewbDevBoxButtonFrameReloadButton
    local lastCount = 1
    for k, v in pairs(NewbDevBoxDisplayButtonTable) do
        if v then
            thisButton = _G["NewbDevBoxButtonFrame" .. k]
            thisButton:ClearAllPoints()
            if mod(lastCount, 3) == 0 then
                thisButton:SetPoint("LEFT", lastOnTop, "RIGHT", 10, 0)
                    lastOnTop = thisButton
            else
                thisButton:SetPoint("TOP", lastRelative, "BOTTOM", 0, -5)
            end
            lastCount = lastCount + 1
            lastRelative = thisButton
--[[
            thisButton:SetPoint(
                VariableList.currentParentAnchorPoint,
                VariableList.currentAnchorButton,
                VariableList.currentChildAnchorPoint,
                VariableList.currentSideGap,
                VariableList.currentYGap
            )
 
            if VariableList.currentButtonCount == 3 then
                VariableList.currentParentAnchorPoint = "LEFT"
                VariableList.currentAnchorButton = VariableList.topAnchorButton
                VariableList.currentChildAnchorPoint = "RIGHT"
                VariableList.currentSideGap = NumberList.actionButtonSideGap
                VariableList.currentYGap = 0
                VariableList.currentButtonCount = 1
            elseif VariableList.currentButtonCount == 1 then
                VariableList.currentParentAnchorPoint = "BOTTOM"
                VariableList.currentAnchorButton = thisButton
                VariableList.currentChildAnchorPoint = "TOP"
                VariableList.currentSideGap = 0
                VariableList.currentYGap = NumberList.actionButtonYGap
                VariableList.currentButtonCount = VariableList.currentButtonCount + 1
                VariableList.topAnchorButton = thisButton
            else
                VariableList.currentParentAnchorPoint = "BOTTOM"
                VariableList.currentAnchorButton = thisButton
                VariableList.currentChildAnchorPoint = "TOP"
                VariableList.currentSideGap = 0
                VariableList.currentYGap = NumberList.actionButtonYGap
                VariableList.currentButtonCount = VariableList.currentButtonCount + 1
            end
]]--        
        end
    end
end

This creates a column of 3 starting with the Reload button and then starts the next column to the right of the last button designated the "top button" of the last column.

Because the table you're cycling through (NewbDevBoxDisplayButtonTable) has string keys, they aren't sorted so you can't guarantee the order the buttons will be in.