apology accepted :) and I want to repeat that I appreciate your genuine interest in the engine and feedback!
I will look into highlight.js and similar libraries, but to elaborate a little bit: One point against it is that right now trash engine itself is quite lightweight and any extra library would significantly increase the file size - and the smaller libraries I tried were somewhat buggy. I was also considering replacing the code editor with a text/visual scripting hybrid solution. So spending time on a syntax highlighting when I might scrap it anyways seemed a bit pointless.