Hi there,
I tested the plugin with those settings. The error it throws is:
Fatal error: Uncaught TypeError: Unsupported operand types: string + int
When GP makes this callback:
$published_time = get_the_time( 'U' ) + 1800;
The get_the_time
function is a core function:
https://developer.www.ads-software.com/reference/functions/get_the_time/
It expects either a String or an Integer value. But looking at that error both String + Integer are being returned, which is something that plugin must be doing. And should be addressed by the plugin developer.
For GP you would to work you would need to disable the post dates with this PHP Snippet:
add_filter( 'generate_post_date', '__return_False' );
Then you can try hooking in the plugins shortcode with this snippet
add_action( 'generate_after_entry_title', function(){
echo do_shortcode('[nepali-date-converter]');
});