Suenilda, Swonild, Suanahilt and Suaneldis are other forms. Source: S.L. Uckelman. "Swanhilde". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2023, no. 1. http://dmnes.org/2023/1/name/Swanhilde.
I believe (based on my meager understanding of German) that this name would be pronounced [svahn-HILD-uh] - "svahn" like "swan" but with a "v" sound instead of a "w" sound, "hild" rhymes with "chilled" and "uh" is like the "u" in "fun" :) Correct me if I'm wrong!
Source: S.L. Uckelman. "Swanhilde". In S.L. Uckelman, ed. The Dictionary of Medieval Names from European Sources, Edition 2023, no. 1. http://dmnes.org/2023/1/name/Swanhilde.