Unfortunately I cannot reproduce it. I've set the Wii language to Dutch and it still works perfectly on my end.
Are you working with a clean configuration for 4.0 or did you copy paste them from an older version? If so, start over clean.
Might be a long shot, but with the Dolphin 4.0-46+ versions, the DX11 has worked like a charm for me. Worth a try ?
I think it's the game itself, just tried the game on another PC and selected Dutch as the Wii language and it came up with a black screen as well.
Garteal: I only imported the Wii saves of the games.
Alajarvi84: DX11 lags for me a lot in SMG 1 & 2 (around 45 FPS), DX 9 however gives me a FPS 55-60 in these games. I thought they fixed the speed for DX11 already, otherwise I don't understand why the DX9 is deprecated.
Because the entire DX9 backend will be removed very soon...
I understand, it would however be nice if they try to fix the speed in DX 11 as in DX 9 before they remove it. But then again, who am I to say this. I bet it's hell of a job to accomplish such thing.
Does DX 9 speed up SMG 1 & 2 more than DX 11 in your cases?
I just own SMG1 and the speed here is the same (around 45-60FPS) despite of the video backend probably due my laptop that isn't fast enough