Yes. The template format is public, in the emolysis/template-sdk repository on GitHub under the MIT license, together with a validator. A template is a folder: a SQL or Python file with typed slots, test fixtures with expected outputs, a short cost note and the platform constraints it needs.
You can write templates for your own recurring patterns and use them in your projects. The library of tested templates that ships with Emolysis stays part of the product, and the SDK package is not published to a package registry yet.
The templates and slots docs describe the format, and the pipeline shapes show what the library covers. See also is Emolysis open source.