The number of dashes for a given column is equal to the longest string trimmed string in that given column - 1 (to include the ‘:’). So if you want increase the width, you can manually add more dashes. If you want to decrease, it won’t work because as far as I know, MD tables can’t do multi-line rows so you can’t compress that down.
You’re also right that I’m not rendering the table, I’m replacing the text with non-destructive edits. Hope it’s still of use!
You’re giving me a quick idea for a new action to “resize” column widths though with a simple dialog.