Buyers and reviewer will not do this.
But I went ahead and waited for full loading. With respect:
If your script requires time to load, show the indicator.
The user should not receive fatal errors if dynamic content has not been loaded.
Consider using Vue/React/Angular if content is loaded dynamically on network request.
You duplicate access checks in network requests. I think you can check access with one request, and not before each.
I do not understand the functionality of the item. Is it for printing bank checks? I think there are separate standards for such operations. Do you abide by them? Moreover, check system is not common in world and this may not be popular for the Envato.