Hello,
Import of all the variations for all the products takes a lot of time and very often the server limits do not allow to finish it and it causes the error of the import of whole the content. Not all the servers allow increasing these limits. That’s why we decided to skip the import of the product variations for every product. WooCommerce documentation clearly explains how to create variable products https://docs.woocommerce.com/document/variable-product/ and we don’t use any special methods or settings in addition. Also we have video tutorial on how to use variation swatches https://youtu.be/LgzC4iK-j6A So, not sure why this is a problem. If you don’t have experience with WooCommerce plugin did you read plugin documentation and theme documentation/video tutorials before start your work?
Regards