А кто это, Дидуля?

Наверное, дедуля))

The old man plays/is playing out of tune, but his self-admiration alongside with his freakiness (somehow) makes up for it in the eyes of his audience. ¿¿¿

I think it’s an excellent translation! But realize that self-admiration has a negative connotation. It’s basically arrogance.

Yes, the same is in Russian. Самовлюблённый (человек) is basically a narcissist. I don't like the way it's used here, but it says it nevertheless I think.

Then your translation is perfect))

Thank you so much! But what about the tense? My guess is we need a broader context to figure it out.

I would keep “plays/is playing”

Also, I would prefer “along with/coupled with his freakiness”

Хорошо.))