It would be possible to have separate lexer styles for function calls, distinguished when they are part of an attribute access expression, as well as field/property accessors. But for the reasons @elextr mentioned, there's no way to really be sure (semantically) what those things are/refer to, it would literally just be based on the tokens in the file and looking for a sequence like `IDENT DOT IDENT LPAREN arguments_list* RPAREN` or whatever.
That said, any work on the lexer/highlighting needs to first be done in [Scintilla](https://www.scintilla.org/) (where the lexer comes from), and should be opened as a [feature request](https://sourceforge.net/p/scintilla/feature-requests/) there, assuming none such exists. For this reason combined with what @elextr said, I'm going to close this Issue.