Here’s a quick way to fake it. Unfortunately, I don’t have the time right now to build you a spiffy Formatting/Config dialog, but this will at least get it working.
void DFInit( ) trans2
Key_To_Window( Ascii( "]" ), "LangCloseParen /LP=C/MC=]" ); // "]" key
Key_To_Window( Ascii( ")" ), "LangCloseParen /LP=C" ); // ")" key
Put that in a file named DataFlex.s in the <MEW>\Src directory. Hit F9 to compile it.
Now, under Tools|Customize|Languages, select your DataFlex language, and hit Edit. In the textbox for the Init Macro, fill in DataFlex^DFInit
Next time you open a DataFLex file, parens and square braces will highlight when you close them. I couldn’t do braces quickly, as that seems to rely on the C support pretty tightly (and I’ve never seen DataFlex, so it may not be relevent anyway…)