Most likely both the Berlin word and the Swedish word derive from the same word in old Platt-Deutsch (the language used by the Hansa empire). Almost 40% of all Swedish words entered the Swedish language through trades with the Hansa empire and Hansa traders settling in the Swedish towns.
Yep, definitely. It's something that can happen now and then for anyone, and nobody knows the cause as far as I'm aware. Luckily, it's pretty rare and easy to get around, but still annoying.
Still, there are plenty of similar cases where it's actually a missing translation or us having entered the info incorrectly. It's impossible to tell without checking the admin interface. :)
I do not think it sounds like the approximant r here or in other examples with a final L. Because the approximant would sound kind of like an English R. - I often hear this final R as an L, too (böcker etc.), but it is just a flapped tongue tip R which is close to an L "by nature".