How to add metric goal in tilde to submit form via JS?

Question

Yandex.Metrica

I set the metric to tilde not in the standard way through the connection through the settings, but simply inserted the js code on the page in the footer. There are virtual pages in the tilde for forms, visiting which activates the goal, but with this insertion of a metric, this does not work. How to fix goals correctly? Working out the goal when clicking on the button or onsubmit is not suitable, because. there is a validation of the form and it is necessary to work out only when the form is successfully sent. It would be nice to put it in the onsuccess block, but how do you do it?