This should actually be really easy to programatically achieve.
I would like to propose some simple enhancements to the “Advanced Tables” syntax:
|Attribute||Wiki Syntax||HTML Transformation||Description|
|colspan||[[cell colspan="2"]]||<td colspan="2">||Allows a cell to span across multiple columns|
|rowspan||[[cell rowspan="2"]]||<td rowspan="2">||Allows a cell to span across multiple rows|
Though we don't necessarily require the th element, I included it only because the “Simple Tables” use them in their syntax. Anything you can possibly do in a “simple” table should also be achievable in an “advanced” table, in my opinion.