Expanding from Switzerland into Germany is among the easiest scenarios for language and distance. The difficulty sits out of sight: currency, the customs border, and the data questions that follow from being outside the EU.
Working across two currencies is not only an exchange-rate matter. Which currency prices are shown in, which the invoice is issued in, how exchange differences are recorded and which your payment provider supports are separate decisions. Added later, historical records stay inconsistent and the correction is done by hand.
If you sell software or services, the practical effect of the border is limited. If you ship physical products, customs, VAT and delivery terms become a workstream of their own; that is a logistics and tax question handled on the partner side. What matters for the systems is that the order flow knows which regime it is operating under.
Switzerland is not an EU member, and data moving between the EU and Switzerland requires a separate basis on the contractual side. Which basis fits your case is a legal question and goes to partner law firms. The consequence on our side is this: which data crosses the border must be visible from the start, and where possible the architecture should not require the transfer at all.
Yes, because the issue is format and fields rather than language. Address format, postcode length, the tax number field and invoice requirements have to work the German way. Differences between Swiss and German usage also show up in the copy; small, but noticed immediately by the reader.
It depends on your activity and it is a legal question we settle with a partner law firm. What matters from our side is that whatever the answer, the invoice can be produced under the correct legal entity and with the fields Germany expects.
Tell us what you sell and which currency you prefer. The first accounting knot usually appears right there.