This is a translation of my post in French below.

The other day we had the dubious pleasure to share our B&B breakfast table with a group of four Bavarians, at least one of whom spoke acceptable French. Our landlady explained to them the various breads, cakes and jams on the table. I was already raking my memory for the German terms for “quatre-quart” (pound cake) and “épeautre” (spelt wheat), but to my great relief, the Bavarians did not seem to wonder, and I was able to keep my linguistic anonymity.

Then, surprise: The very ordinary red fruit jam (“confiture aux fruits rouges”) baffled the francophile Bavarian, and our landlady listed the red fruit it contained for him.

I thought about it afterwards. The problem had clearly not been the terms “fruits” and “rouges”, since he had repeated them correctly in English as “red fruit” (why in English? search me). But it is true that in Germany you wouldn’t find a “Rotfrucht” jam. “Waldfruchtmarmelade” (literally “forest fruit jam”), yes, with woodland strawberries, blackberries, blueberries (and you wonder why they are not called “red fruit” in English…), but not a combination of strawberries, raspberries and cherries.
Turns out it was a cultural jam, not a linguistic one.