Toad's code complete feature missing function?

Is there a way to get Toad's IntelliSense feature to suggest Functions() like REPLACE(str, find, replace)

Toad Edge does this for (user-)defined function/procedure-type objects, as snap below shows, but I think you're talking about the built-in functions, like REPLACE(), SUBSTRING(), LTRIM(), etc.
and it doesn't appear that Toad Edge allows for type-ahead on built-in functions.

Best to submit an enhancement suggestion on Toad Edge's Idea Pond, or alternatively, Quest can document the enhancement request for you.