Filter validation message when the item has stock available but not as many as the requested amount.
Apply to all forms.
add_filter( 'gplc_not_enough_stock_message', 'my_custom_function' );
Apply to a specific form.
add_filter( 'gplc_not_enough_stock_message_FORMID', 'my_custom_function' );
Apply to a specific field on a specific form.
add_filter( 'gplc_not_enough_stock_message_FORMID_FIELDID', 'my_custom_function' );
Modify the Message That Is Displayed When the Stock Left Isn’t Enough.
This filter is available since GF Limit Choices 1.6.