i don't see any relation between moderators and modifications other than the common 3-letter prefix. I was about to submit this post but then @jacob1 reminded me that There are 2 kinds of modifications out there: Lua (not an abbreviation) and C++, C++ is when you download the source, compile it, and then modify and distribute. Lua is when you make a script, an add-on to the game, and you only have to distribute the addon.
But ... it's best to actually have knowledge of c++ before you try and mod it.
And Lua is an entirely different way. You can't edit as much, but it's a lot easier to do than using c++. It's mostly used if you just want to make new elements in tpt.