Hi there @Juneinquiries,
Welcome to the Community and thanks for posting your question here!
I understand you are having some difficulty with some of Klaviyo’s code snippets, since migrating to Shopify 2.0.
Shopify 2.0 was introduced to allow developers more freedom to edit code in JSON instead of Liquid template theme files within Shopify. The main difference you'll face after upgrading to Shopify 2.0 is that most of the features now rely on JSON templates. Shopify has created this guide, which provides step by step instructions for converting a Liquid template into a JSON template, and moving any required Liquid code into sections that you can include in the new JSON template.
Hopefully after going through the JSON templates and reviewing their guide, you should be able to find the liquid files. If not, please report back!
Have a good day,
Alex