1. It wobbled after unpacking it. Luckily i could fix that by bending the case a little bit. Maybe it buckled because of temperature difference during shipping or so. No big deal.
2. The up-arrow key is misaligned, as mentioned in the "Filco Camo build quality prob?"-thread.
3. After only this short amount of time (less then a month), i hear a pretty strong and loud "spoing" sound from the springs in some switches, that i am sure should not be there. I don't know if this is normal, but it sure is pretty annoying.
4. The general audible feedback from the keys is very diverse. Again i don't know if this is normal, but it doesn't sound like a consistent unity.
Well first of all, this may simply be a case of Buyer's Remorse (which is a form of post-decision dissonance). However, I suspect that what is happening here is a mixture of a little Buyer's Remorse, a little shipping damage, and a heavy dose of "German culture shock at low quality control from Asian manufacturers" which is a culture-specific phenomenon that is not described by American Psychology (the DSM-IV is notoriously bad when it comes to the diagnosis of non-English speaking people). The OP is German, and German people expect everything to be made in the way a German person would make it, i.e., it should be made with exceptional attention to detail and high quality control. However, manufacturiong in China (or Taiwan), is entirely different. German consumers are willing sacrifice price to improve quality, whereas the Asians will sacrifice quality to keep the price (are more accurately, the cost of manufacturing) low. Here we have a German person who thinks he is spending more money to get higher quality (as is customary in Germany). In America, we have learned that such a tradeoff does not always exist, and that higher priced goods are not necessarily of super high quality. All that you can really expect from a Filco is that it is better than a rubber dome keyboard. With that preface, I will address the specifically enumerated concerns of the OP:
1. Wobbling: your keyboard got bent during shipping. Why? Poor packaging. (Saves money.) Fix? Try GENTLY bending the metal plate back into relative flatness with your hands. If it is irreparably bent, I would say this is good cause for an RMA. Filco is to blame for inadequate packaging used for shipping, especially since they charge the customer for shipping and handling. (Notice to Filco Distributors: Shipping and Handling are NOT a valid means to generate extra profits.)
2. Mis-aligned Arrow Key: Manufacturing defect. Everything that is manufactured anywhere in the universe will have some variability. No two items will ever be exactly the same. This is how the laws of probability work in our universe. However, the physical difference between each manufactured item will most likely be very slight (within two standard deviations, or "two sigma" as it is commonly known), but on very rare occasions, you will get an extreme outlier (beyond six sigma), which might be what you got. Fix? You can buy a set of new arrow keycaps over the internet -- you can get them for $4 or less, and you can get them in a rainbow of colors.
3 & 4. "Spoing": this is an entirely subjective complaint about the sound of the keyboard. However, I don't think anybody should minimize it, or doubt that the OP really hears it. I believe he hears it, and I believe it bothers him. On the other hand, I am not willing to say that it is a manufacturing defect. What is causing the spoing sound? I honestly don't know. I also don't know if the spoing sound is simply the normal sound of a Filco keyboard. A Filco will make a particular sound when the keys are pressed, and that sound has a vaguely metallic resonance or tone, due to the metal plate inside the keyboard. This is entirely normal. So the question becomes, is the OP's spoing sound unusually bad? I have no idea, and this gets into the whole Filco ping issue, which was the subject of so much
sturm und drang, and so little beneficial discussion. All I can say is that if it really bothers you, you may have to try to return the board with the explanation that the product is not suitable to you, even though it appears to be working correctly.
Well in conclusion, I would say that if the keyboard is really bent then you should RMA it, as that should not happen. Second, maybe the bent metal plate inside the keyboard is producing an unusual sound, or it is making some keys sound like a "spoing". Third, when looking at the
gestalt, i.e., given the bent keyboard, and the misaligned keys, and the "spoing", maybe you have sufficient grounds for an RMA. I have two Filco's and I am extremely happy with them, and I would like to see you have the same satisfaction with your keyboard, and I'm sure Filco would too.