Full Name Desired

Neva/Niva

Preferred pronunciation: nee-vah

Norse

We have found the name Sunneva - <Sunneva> is documented from "Jensen's Scandinavian Personal Names in Lincolnshire and Yorkshire" (pp. 271 - 272) sn. Sunnifa. Commentary pointed out that per the google books preview of FJ, <Sunneva> appears in the Latin ablative, 1121-27; based on this it is after the cutoff for mixing Scandinavian and English.

Russian

Niva is found as a period masculine name in Russian (нива), although it's a feminine word ('cornfield').
- Niva (m) -- Ivan Niva, executioner, 1558. Wickenden, 2nd edition
- нива (fem) cornfield per SlovoEd dictionary (note that maize is out of period).
- нива means ager (Latin, field), arvus (Latin, plowed), пашня (plowed field), поле (field), oобработанное подъ пашню (worked/cultivated under plowed field) and dates to the 12th century per Volume II pp. 445-446 of Sreznevsky, I.I. Материали для Словаря Древней Русского Языка (_Material for a Dictionary of the Ancient Russian Language_) available online on various sites (and downloaded on Sofya la Rus' computer).
You might have to use the masculine form of in rauða (inn rauði) to make the name consistent for gender, so Niva inn rauði
Unless support a feminine Niva/нива, which would allow Niva in rauða...

Absence of evidence is not evidence of absence for Russian women's names because:
1. Men's names are attested more than women's names by at least 50 to 1 in Wickended, even though he was specifically looking for women's names
2. Russian men fairly frequently used grammatically feminine names, as can be seen in a brief survey of Wickenden, see Sofya la Rus' notes at Gender Bending Names for more information
Names used by both men and women (all per Wickenden): Bela (white), Belka (squirrel), Boika (fight), Desha (ten), Dobritsa (good), Dragin'ia (dear), Groza (terror), Kalia (dirt), Kasha (porridge), Kata (rolling), Krasa (beautiful), Kudra (curl), Kuna (quill), Kunka (marten), Leva (lion), Liuba (love), Maliuta (small), Mana (attract), Manka (lure), Miakusha (soft), Milenia (dear), Mira (peace/earth), Nedelia (week), Olenka (hart), Ovtsa (sheep), Paraskov'ia (Friday), Radka (joy), Sel'ianka (peasant, of the field), Shchuka (pike), Sina (blue), Vera (faith), Vladyka (rule), Voina (war),
Plant-based names (ibid) and also Botanical Bynames in Russian:

many grammatically feminine plant names, hard to document as feminine given lack of documented women's names...

Ol'kha (f) -- dim of Ol'ga per Wickended 2nd edition, but ol'kha also Alder -- Ol'khin (from ol'kha, 1540) per Botanical Bynames in Russian
Riabina (m) -- "female [sic] slave." Riabina, peasant, 1495. but also mountain ash (tree) per Botanical Bynames in Russian
Sosnin (byn) -- "pine." Osif Iakovlev syn Sosnin, 1573. Doesn't specify if parent, Sosna, was male or female (although most likely male)
Ivin (byn) -- "willow." Belianka Ivin, Sviiazhsk boiar's son, 1614. Ditto.

In Rauda - ‘inn rauði’ as an adjectival byname meaning "red" on page 26 of Geirr Bassi's The Old Norse Name shows. This has been modified to the appropriate feminine form following the rules given on page 19 of The Old Norse Name.
hin Rauða - is the feminine form of <hinn Rauði>, a descriptive byname meaning 'the Red,' from The Bynames of the Viking Age Runic Inscriptions by Lindorm Eriksson; https://www.s-gabriel.org/names/lindorm/runicbynames/body.htm#start, originally published in KWHSS Proceedings 1999. Also found in FJ, p. 216.