OK, but you are still doing this:
'tax_query' => array('taxonomy' => 'tribe_events_cat','field' => 'slug', 'terms' => $term->slug)
Important Note: tax_query takes an array of tax query arguments arrays (it takes an array of arrays)
We'd love to help more, but I'm afraid the amount of support we can provide for custom coding is especially limited here on the free support forum.
Good luck!