From the Help file:
• Pad parentheses - If selected, a space is inserted after the open parenthesis when a parameter name is automatically inserted. In addition, if you type a close parenthesis after an automatically inserted parameter, it will insert a space before the close parenthesis.
Do you mean that you typed "Foo(" and then the editor automatically inserted "barParam" like so "Foo(barParam" instead of like "Foo( barParam"? That's what the "Pad parentheses" option in Context Tagging is for. The option only controls spacing
when SE automatically fills in parameter names for you. If SE didn't fill in a parameter name, then the option wouldn't have been applicable.
There is no option in SE yet that always inserts a space after an opening paren, or after comma, or before a closing paren. Ideally Adaptive Formatting would detect the style you want, and typing a closing paren would reformat the preceding parens to match the dominant style in the file.
If you always want a space to be inserted after an open paren while you type, you can write a macro that inserts "( ", and bind that to the open paren key. If your needs are more sophisticated, you can add things like a close paren macro that automatically strips whitespace between an empty "( )" pair. Ideally I wouldn't need to write macros to get the behavior I want, but realistically there are a lot of people out there with differing expectations, so I'm happy that I'm able to write macros to customize the behavior to my liking.