Hi again,

#1/ Please update PHP version up to 7.4, your Php version ( 7.0 )is too old and may cause errors

#2/ Please activate the child-theme and add your customizations here, adding the code directly to the main theme will result in code loss when you update the theme version

#3/ The error you posted above was caused by the wrong custom code you added, I fixed it and added it to the child-theme:

Error: add_filter( 'the_title', 'shorten_woo_product_title', 10, 1 );
Had to change it to add_filter( 'the_title', 'shorten_woo_product_title', 10, 2 );
Since you are calling 2 variables in the function below:
function shorten_woo_product_title( $title, $id )