Most themes using ACF are custom and don’t get updated. There is nothing built in to ACF that to modify the content and markup of your a site. There are a few themes that use ACF, but most developers that use ACF are building custom themes.
The solution you have is what I was beginning to suggesting, but without the details I was asking for I could only go so far.
The only difference in what you did and what I would have suggested is that I probably would have used an existing field
$staffname = get_sub_field('name');
$id = preg_replace('/[^a-z0-9]+/' '-', strtolower($staffname));
