Why tween individual letters? I've seen animations that move specific code blocks or keywords, to show the actual movement of those blocks, but individual letters just feels like noise.
That being said, I do like the overall idea of animating code changes. Calls back to that old Facebook sketching app[0] that would let us share replays, and I am a fan of the stories that Gource[1] can tell.
Ultimately, though, the sequential text file is a bad metaphor for code. Best thing for it is to split your modules across files.
0. Can't remember the name of it, but something similar is https://sketchtoy.com/