Typical German contracts that I get to translate will start off by naming the parties and in brackets defining a short name, e.g. im folgenden: “Käufer” (hereinafter referred to as the Seller).
That’s similar to the English-language approach. I usually remove the inverted commas. It is not necessary to capitalize seller, at least in England, but my clients appear to expect it.
After this, the contracts usually never use the term Käufer or Verkäufer again! They will write Vertragspartei, or name the company, but having defined the terms they drop them. I have sometimes seen a party referred to in four different ways in one short contract. Or having defined die Produkte (the Products), the writer thereafter refers to die Vertragsprodukte (the contract products – presumably this can’t be capitalized if it hasn’t been defined).
As a result, a translator’s note usually needs to be made. One doesn’t want to use several different terms in English, even if it is easy to do so (which it sometimes isn’t), but nor does one want to misinterpret.
Incidentally, I would love to use the company name instead of Seller, especially where the defined term is hard to translate, but this is usually rejected, possibly because the customer wants a text that can be used in future with a variety of parties (in which case, I need to know that, so I can ensure the translation is not gender-biased, for example), possibly just out of a feeling that this is too great a departure from the German.
Anyway, it’s clear why the defined terms are not used consistently – it’s because the drafter grabbed bits from a variety of sources and did not adapt them. That happens with English contracts too. And the drafter is sometimes not even a lawyer. But still, the prevalence of this in German contracts always surprises me.
Why is it so? I think it must partly be because the German drafter doesn’t feel the definition of terms is needed for clarity. This refers to shortish contracts, of course, not the huge ones preceded by dozens of definitions.
Incidentally, contracts online are often standard contracts intended to be adapted by the user, so they do not vary the names of the parties, since der Käufer/die Käuferin (the latter often refers to a company rather than a woman) are the only terms they have.