As I hadn't heard back from you and couldn't leave the live site broken, I rolled back to template version 2.0.1, which is working fine. After having to clean and reinstall four sites due to the recent SP Page Builder vulnerability (which has been a real nightmare), I just hope this older template version is secure.
Therefore, please disregard the links I previously sent, as you won't be able to see the error online anymore.
However, if you would like to investigate and run some tests, all the access credentials I provided are still valid. You will find three versions of the template installed on the backend, which I have detailed in the hidden section below.