Just a few comments here about misinterpretation of meaning. Most of these mistakes come from small tricky things about the German language, especially with poetry.

Sie war auf dem Schlachtfeld daheim – she felt at home on the battlefield

Er reitet durchs Feuer – he rides through the fire (here you had past tense, where the past tense in German would be 'ritt')

Siegfried vor Burg Isenstein – Siegfried in front of/before Castle Isenstein (I think you mistook 'vor' for 'von' in this part)

Ist neun Nächte mit ihr allein – he spends nine nights alone with her

Unsterblichkeit war der Preis – immortality was the/its price (you had 'it's' here, which is the contraction form for 'it is.' The possessive form is 'its.' A good portion of English speakers get this wrong.)

Sie schworen sich Liebe – they pledged/vowed their love for each other (here you mistook the 'sie' for 'she' when it was actually 'they.' The way to tell this is the past tense 'en' ending on 'schworen.')

So sei unser Bund – So shall be our covenant/pact (you had 'gebunden' in mind here I think, meaning 'bound,' but 'Bund' means 'covenant' or 'pact' in this context).

Durchs Leben und in den Tod – Through life and into death (in +accusative case usually corresponds with English 'into.' Accusative case here shows the direct movement of something into something else, whereas Dative case would denote the static existence of something inside something else.)

Nimmt Siegfried Krimhild zur Frau – Siegfried takes Krimhild to/as his wife (I think this was just a misunderstanding of what 'Frau' means in this context, since the word can be both 'woman' and 'wife' depending on context.)

So brach er dein Eid – breaking his oath (so here would mean in this way/by doing this, referring to taking Krimhild as his wife, so breaking his vow/oath gets this meaning across).

Verwirkte sein Leben – forfeiting his life (Siegfried takes Krimhild to wife, breaking his vow and forfeiting his life)

Die Frau Brunhild – The Lady Brunhild (Maiden is more like Magd or Maid)

Getaucht in flammendes Rot/begrüßt den Geliebten – Awash in flaming red/she greets her beloved ('getaucht' is like 'submerged' here, so I think 'awash' is a good poetic word choice, showing that she's submerged in firelight.)

Und reitet mit ihm – and rides with him (just past tense mistake again)