I love that song. Happens to be my favorite.

I love that song. Happens to be my favorite.

Hi Shaky,

I can’t work out from your voice recording what your question is, sorry.

I love that song. It happens to be my favourite. = I love that song. By chance (the chance that they are listening to it now and talking about it) it is my favourite one.

In my native translation somebody marked - Happens to be my favorite. - as past indefinite was he right?

Here are the possibilities:
‘Happens to be my favourite’ might be heard in informal speech as a kind of ‘shorter’ version of the full sentence. However, the full gsentence would require a subject:
That song/it happens to be my favourite (song).

‘happens’ is a linking verb:
to do or be something by chance
happen to be/do something

Examples
She happened to be out when we called.
You don’t happen to know his name, do you?
This happens to be my favourite restaurant.
The door happened to be unlocked.