I am 99% sure that battery will be assembled in China, BUT if the German reseller is the company that is honouring the warranty and they are easy to return a battery to, that might be enough to make it tempting.
A local warranty, unless you can afford the risk, is the safest solution. Again, I've taken the risk and came out with only a couple of disappointments. Often, when covering a warranty, a china source will ask the battery buyer to open the case and do some testing. NO! JUST NO! Lunacycle, a USA source, used to encourage the kit builders to do the same. It's dangerous! After selling and supporting batteries for a decade + I have now stopped the risk-taking. Even though I still have all the battery-building tools and electronics. I'm old, and it's a project not suited to a post-stroke brain, <wink>