No it isn't. This is where the Black Forest is:
The marker is nowhere near it. For fuck sake you posted maps showing it's in a different spot. You can clearly see the Rhine on the in game map and it's so far off it's not even funny.
So odds are pretty damn high that the forest that's not called the Black Forest and not near the Black Forest is in fact not the Black Forest.
...It never ceases to amaze how retarded people get when you dare point to them how strong Fate is because they end up doing retarded gymnastics like that...
You know what happens when you press the Germanica icon?
The Dark Forest
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You get the Black Forest as a name of the place... and I already know some retard is gonna go "But that's called the DARK Forest so it can't be the BLACK Forest" because they did it to me and the answers the same:
It's in the same fucking place where the Black Forest is, the Dark Forest is the Japanese version of the name Black Forest(Which is extremely obvious that's the case) and it literally is in the same place that the Black Forest is in real life. Arjuna vaporized the whole ass thing by his and Chaldea's own take, cope, seethe, mald.