I’ve just known from japanese fan.

Tsuna calls Hibari with 「ヒバリさん」, instead of 「雲雀さん」. When Tsuna called Hibari in manga, it was written with katakana! I didn’t know about this.

Apparently, this is the reason why hibatsuna japanese fans usually used 「ヒバリさん」 instead of the kanji.