The `comment_single`, `comment_open` and `comment_close` settings only control the `menu->edit->format->comment ...` commands. They do not affect the syntax lexing, its coded in the properties lexer in C++ to use `#`, `;`, `!`. The syntax lexing is part of the [Scintilla project](www.scintilla.org) which we simply use.
You could ask on Scintilla that it be made a property of the properties lexer as well as being coded.