You're welcome !
Well, to make a callback on the clicked link, that would be out of Grocery Crud since the click is handle by the browser.
That means you could either add a onclick='yourcallback();' on your link, and make a JS function yourcallback() , or you can init a click event with jQuery, outside GroceryCRUD.
Make sure you load jQuery or any library you use to handle the clicks if you use a library, and that's it !
If the callback is supposed to happen after the link is clicked, on the target, that would be server-side !
Let me know if you understand and feel free to provide me more details.
I personnally don't want to get into the GCRUD React scripts, they can be updated any time and I'm not a React developer, so I handle everything else in my own script.js using jQuery.
That's how I made a "preview" button for instance, I have a table "articles" with a text field, and I added a preview button near the Save button to achieve custom events.