Get Filtered Data Range in a Table
Public Function GetFilteredTableRange(ByRef targetTable As ListObject, Optional ByVal includeHeaders As Boolean = False)
    '/ given a table, return a range object that contains only those rows which are visible
    '/ Do this by looping through tableRows, adding all visible rows to a unionRange


Newlines
are
cheap.

In Python, you always aim to keep your lines shorter than 80 characters long. I personally think it's a good practice to keep that size as a guideline in other languages as well. Your first line is 120, 1.5x my proposed maximum.

Added benefit of trying to stick with a maximum is it keeps you sharp. You're forced to think whether it's absolutely necessary for that line to be that long. Long lines are not fun to read, so try not to make them longer than necessary.

Public Function GetFilteredTableRange( _
    ByRef targetTable As ListObject, _
    Optional ByVal includeHeaders As Boolean = False _
)
    '/ Given a table, return a range object with only the visible rows.
    '/ Do this by looping through tableRows,
    '/ adding all visible rows to a unionRange.


That's how I'd do it, but I'm not up to par with VBA coding standards.