First, let me thank you, f+d+k, for writing ReNoam. It looks very useful as it is, and I look forward to using it to experiment with CFGs and PCFGs.
As for Clip, it looks interesting, and I tried to install it, but it seems to be incompatible with Renoise 3.1.0b4, it hasn’t been updated since 2013, and the website hosting its official documentation  does not resolve (though I did find the docs on another site ). I think it’s fair to say that project is dead.
If I was going to roll my own L-system implementation, at this point I’d probably start with something like XStream, which is a much more recent and living project, which is compatible with the latest version of Renoise. I need to re-learn Lua (it’s been a long time), along with XStream, and the Renoise API for that to happen, though, which might take a while.