As a native German speaker, I can at least say that knowing both German and English doesn't really help in understanding the text. Not even the most "dumbed down" version - ok, he's apparently saying something about his wife, but no idea what exactly. And when I read "shyne (Modern English "sheen" but German cognate is closer)", I was even more confused. "Sheen" is the property of an object that is shiny, which in German would be "Schein", but because it is applied to a woman, I assume that the "cognate" he refers to is "schön" (beautiful)?
I, too, find it confusing. The "German cognate is closer" is not helpful!
I think the ö is significant. It could correspond to English ē, but not ei, -ine.
Under sʜᴇᴇɴ, Partridge [1] states that OE scēne, scȳne are related to G schön, from PIE *skauniz "Ultimately, to E sʜᴏᴡ."
I think we have two compartments here:
1. ö/ē words - schön, E shown, shewn. Under Partridge [1] sʜᴇᴇɴ
2. ei words - G schein and E shine. OE scīnan, under Partridge [1] sᴄᴇɴᴇ
[1] My favorite reference: Eric Partridge: _Origins: A Short Etymological Dictionary of English_. More concise than the OED, and you can carry it.
As an English speaker, I'm delighted by the borrowing "ser schön". It is the highest grade in English catalogs of ancient coins. "Shiny" is not a good quality in ancient coins!
Another Modern English cognate even closer to shyne than "sheen" is "shine" (and obviously the German "schein"). The words for "beautiful", "fair", "bright", "shining", "well-reputed", "righteous" have a long history of being related:
https://en.wiktionary.org/wiki/schinen#Middle_English (to shine, to appear)
https://en.wiktionary.org/wiki/skyr#Middle_English (clear-coloured, pale, light, luminous, radiant)
https://en.wiktionary.org/wiki/sciene#Old_English (beautiful, fair, brilliant, shining)
https://en.wiktionary.org/wiki/Reconstruction:Proto-Germanic... *skīnaną (to shine, to appear)
https://en.wiktionary.org/wiki/Reconstruction:Proto-Germanic... *skīriz (pure, clear, sheer)
https://en.wiktionary.org/wiki/Reconstruction:Proto-Germanic... *skauniz (beautiful, shining)
and ultimately the PIE
https://en.wiktionary.org/wiki/Reconstruction:Proto-Indo-Eur... *(s)ḱeh₁y- (to shine)
There are cognates absolutely everywhere in modern Germanic languages:
https://en.wiktionary.org/wiki/sk%C3%ADr#Icelandic skír (bright, clear, pure)
https://en.wiktionary.org/wiki/skir#Swedish (sheer, delicate, shining)
And even in Slavic languages:
https://en.wiktionary.org/wiki/Reconstruction:Proto-Slavic/s... *sijati (to shine, to illuminate)
Skauniz was even borrowed to Proto-Finnic and highly conserved in modern Finnish, Estonian, Ingrian, etc. which all have kaunis meaning "beautiful"!
https://en.wiktionary.org/wiki/Reconstruction:Proto-Finnic/k... *kaunis
Words to do with light are so subtle between German and English. Like Kraftwerk tells me neon lights are "schimmerndes" in German, which I will take their word on, but they also say they are "shimmering" in English which is definitely not true.
scyn/schön/sheen are a different root from schein/shine, for what its worth.
Also I realise now "forlet" is very archaic in modern english whereas "verlassen" is very common in modern german, which would have helped.
Knowing German would mostly be helpful for understanding the grammar of Old English. The three genders and four cases, participles prefixed with ge-, verbs like sindon (=sind). There are tons of cognates with German (like þurh = durch) but they're hard to recognize immediately unless you know the kinds of sound changes that are common.