Interesting topic!
I'd like to add that Lénia is sometimes used in Portuguese, not as a variation of
Lena (which isn't used as a full name) or as a nickname for
Helena, but rather inspired by Russian-sounding names that were popular in Portugal in the 70s and 80s:
Cátia,
Tânia,
Sónia,
Nádia,
Ânia, etc.
Other similar "made up" names used in Portugal include
Dânia and Vânia (
Vanya) as a feminine name.
So I support your theory that, in both languages, Lénia / Lenya was invented as a name as a "natural" alternative to other similar-sounding popular names.
This message was edited 1/14/2023, 8:45 AM