There's been confusion between the original products and the international English Dubs throughout the entire Rebirth of Mothra trilogy. As a rumor started in the west from a fan name, this fan name was named "Mothra Leo", this name was taken from a song with the same name of which the Elias sang as it cocoons in its first film.
In Japan, this Mothra iteration is typically referred to as "Mothra" or "New Mothra" and not the name "Mothra Leo", even in the film's original product with the English subtitles and English dubs, they don't mention the name "Mothra Leo", they just mention "Mothra".
Meaning that its all Mothra in the RoM trilogy and that Leo doesn't appear in the trilogy at all, only for Godzilla Island.
As evident by the title "Rebirth of Mothra" it would be centered around Mothra as a whole, and not a male Mothra. If they did confirm it would be a male Mothra in the film, they would've changed the film's titles to "Birth of Mothra Leo" (1st film), "Rebirth of Mothra Leo" (2nd film) and "Rebirth of Mothra Leo 2" (3rd film)