Piece of junk refers to something that is cheap, shoddy, or worthless. It can be used as an oject as in "This piece of junk won't boot." or a modiying adjective as in "This piece-of-junk computer won't boot" (with or without hyphens).
Related adjectives can be used with the name of the device. These include:
"Junky", "shoddy", "trashy", "lousy", "worthless", "crappy" (oh, and, of course, "shitty").
Boat Anchor which merely means the device is only suitable for that purpose. "This computer has become a boat anchor" (Urban Dictionary, definitions 2 and 3, Ham.net shows the term used in practice.)
Doorstop similar to "boat anchor". "This computer only works as a door stop now."
Junk Box No longer suitable for anything except to be cannibalized for spare parts. (See wikipedia.) Usually this refers to just the parts themselves, already disassembled and collected into a box. But it parallels your German reference, so I thought it was worth adding.
We also refer to some things as "hangar queens", which is alludes to aircraft that spend more time in repair than they do in service. Any products that can't get through the production process may be relegated to being hangar queens, with hopes that someone will eventually figure out how to repair them.
Pace Dan Bron, the obvious word is waffle:
[mass noun] British Lengthy but vague or trivial talk or writing:
we’ve edited out some of the waffle
[ODO]
This may be related to the German schwafeln, I suppose. It fits your description of "redundant, overcomplicated and filled with irrelevant details or trivialities." There is a verb waffle as well, which means to produce waffle.
Best Answer
When in the 1800s? Toff would be the perfect choice here, but it isn't found any earlier than 1851, and I would be shy of putting it into the speech of anyone until at least 1855 (maybe a bit braver if they were in the Midlands, East or South East of England).
After that though, it would be a common word that matches your description perfectly.
(It's still in use, but not as much as before, having peaked in the first half of the 20th century).
Edit: Comment says this is set in the very beginning of the 19th century. That rules out toff and even haw-haw (around 1825), and beerage is right-out (1880s).
His nibs is an interesting example, but just too late (first attested 1821).
You could take a punt on haw-haw and his nibs on the basis that the first spoken use is likely slightly earlier than the first printed, but it would be a stretch.
Nob is an interesting one and might be apt. It's often understood as a contraction of noble, but while that's probably an influence, white-knob also spelled white-nob is found in the late 18th century until early 19th meaning an upper- or upper-middle class person in reference to the white wigs they would wear and it got contracted to nob. Hob-nob was likely also a further interest.
In any case, nob hits your meaning and was in use in your time, and white-knob also hits it, was in use, and has firmly died-out since, so it might be favoured as giving more temporal flavour.