Adding matching patterns for leaf nodes #3

It may be that there already is a way to do this without adding a pre-walk, so please let me know.
I am trying to detect $Delta E$ as one single leaf node instead of two. It's not possible to combine leaf nodes and ideally I would just like to be able to add a a pattern which has higher priority over others (such as multiply), which forces specific combinations of symbols to be treated as a single leaf node. I didn't find anything in the docs about this and I kind of don’t want to process the entire tree just to find and merge these edge cases, but ideally do it at the parsing stage. I tried using $#box($Delta E$)$ and this works somewhat well, but I find it clumsy to write. I ended up using this pre-walk, but I think it should be possible to do as a parsing step.

#let pre(it) = {
  for i in range(it.args.len()).rev() {
    let arg = it.args.at(i)
    if type(arg) == dictionary and arg.head == "mul" and (arg.args.at(0).at("text", default: none) == "Δ") {
      it.args.remove(i)
      it.args.push(arg.args.join([ ]))
    }
  }
  it
}