(по)репетировал музыку для песни сегодня

As a rule, you can’t use a past adverbial with the present perfect, so the only way to interpret this today is that the day hasn’t ended, in which case it has a meaning of ALREADY. Perhaps it would do to add уже to your translation.

Thank you for the translation grumbler!

Uly, thank you for your comment. Do you mean “today” is a past adverbial? Sorry, I couldn’t understand fully…

It can be past at the end of the day, and present if the day hasn’t ended.

https://www.smissle.com/reference/present-perfect#h.8xe0fw4fw3bp

Uly, thank for the website! I finally understood!

So glad it helped :)