Fernweh basically means to yearn for the far. It's the of opposite of homesick (Heimweh in german).
In my opinion the toast is still one of the most solid puzzles there are in regard to tdw or raxxla so excuse my tinfoil as i dive in a little
My translation from german to english (am native german):
"To the Jewel, that shines at the forehead of the mother of all galaxies! To the whispers in the blackness of space, the siren in the deepest nothing! To the parents grief, the lovers woe (lament works too) and yearning of every vagabond! To Raxxla!"
The main differences being:
They chose to write forehead (Stirn) instead of brow (Braue), but seeing it as calling it the middle or the focal point of something/place gets across either way, more visually speaking (trying to find the eyes) it would place the supposed jewel kind of differently. Interesting fact, "Gestirn", is a german word for light emitting or reflecting bodies in space.
"Stirn" can also mean a front facing part.
Mother of all galaxies seems to be the implication of the original english text too imo, it just gets specificly pointed out in german, don't know why (could just as easily been "Mutter der Galaxien" which would have been a perfect fit).
Also, the german text does not only refer to A "whisperer" but general whispers, but refering to the siren in the same sentence just like the original, makes the source of the whispers kind of singular again. "Schwärze" could be translated to darkness but "blackness" is a much closer. Of course the darkness of space tends to be black so no big news here but still a wierd choice of words.
The deepest nothing is also a wierd choice as Quoted OP stated The Void is also called the Void in the german translation of the game, meaning the void mentioned in the toast could be a entirely different place to the one on the map.
Rover apparently is just an older word for vagabond so yeah, "Vagabund" is just Vagabond.
The difference in wording and word count could mean one of three things:
1. the hints the toast gives are even more vague than we tought OR just partially with more specific information troughout different translations
2. there is a specific sequence or phrasing to be found in the toast, respective of the languages structure and/or poetic customs, so the changes are on purpose
3. bad translation
if the first option is believable it would mean that:
-the placement of the "jewel" is more of a central object than lying between two "eyes"
-the mother of all galaxies is not Cassiopeia, but maybe something either more cosmological or an even more important name giving entity
-witchspace not being mentiones could mean either its not important or the english translation has the next piece of info needed taht identifies the blackness as witchspace
-the void in the toast is not the void we know
Option two reeks of spacemadness so i stay away from that until my options run out.
of course bad translation is the easiest option, but the toast itself is not arkwardly worded at all, it all fits well, just some facts are off, so either the translator had some freedoms in translating the toast (which would be suspicious if considered a hint), or it was just not that important to get right (which would atleast exclude the toast as a piece of the puzzle).
I picked this toast apart time and time again, in german and english alike, thought id chime in to clear the german translation.
Happy Hunting o7