Thank you for the detailed explanation. Over the past couple of months we have had all kinds of custom requests for things that people want WooCommerce Predictive Search to query and return results for, from custom meta to custom taxonomies to just today a request for the WordPress generated post ID.
I believe we have developed a solution that will accommodate most folks and are in the process of testing it at the moment - expect that we will be releasing it Saturday in the Pro Version.
Briefly the feature upgrade will:
1. Add a Predictive search 'Focus keyword' meta to each page and post, similar to what you are doing with custom fields. You enter 'keywords' that you want the product to show in the search for. In your example if the user starts typing 'powerful' then the 'Apple mac' product will show in the search dropdown.
2. If you use Yoasts WordPress SEO plugin you will be able to check a box on the admin panel and the plugin will also do the same with any 'Focus keyword' set in that plugin. This is in addition to any Predictive Search 'Focus Keywords' that you might set.
Adding these features we think will give most admins the very good flexibility and power in optimizing their products, posts and pages for site search.