Hi,
Well, unfortunately there is no option to disable the search in category/term titles, it is hard coded. However, if you are okay with a direct code modification, it might still be possible.
To do that, follow this guide:
1. Before starting, make sure to have a full site back-up just in case
2. Open up the wp-content/plugins/ajax-search-pro/includes/classes/search/class-asp-search-terms.php file on your server via FTP
3. Replace it’s contents with this
4. Save the changes
This should do the trick, as the modified file does not contain the title query.
I think I can add an option in the upcoming release to disable search in the term titles, so this change wouldn’t be neccessary after that.