Hi!
I would love Nertha or Nerta because they are more similar to the original
Nerthus.
I agree with you that
Hertha is warmy and familiar because also the word 'earth' share the same root. To me
Hertha is similar to 'heart' too so all there words (hearth, earth, heart) make
Hertha red, kind and cosy.
Out of your combos I like:
Hertha Rose(mary)
Hertha AmyHertha EulaliaHertha EuphemiaHertha RosamundHertha RosalindHertha IreneHertha Imogen (another classic misspelling!)
Hertha DaisyHertha PrimulaHertha CosimaHertha RoxaneHertha RosalieHertha PrimroseHertha Maud(e)
Personal Name Lists
https://www.behindthename.com/pnl/125456