Hi Remora !!!
Marjatta is not odd to my ears as one of
Maria diminutives here in Italy is
Marietta (same pronounciation but read ma-RYET-ta).
She had a sad story according to what I read in this link but her son will be a
King. It is said that it was inspired by Virgin
Mary right?
It has the same vibe of
Marietta: a nickname for an elderly lady born in years 1930-50. I personally would not use it eccept as honouring.
I like these combos:
Marjatta EsterOlga Marjatta
Personal Name Lists
https://www.behindthename.com/pnl/125456