I noticed that the Fabuland minifigs are listed under "Minifigs" instead of "Non-buildable Figures (Duplo, Fabuland, etc)".
As there are 8000+ parts in "Minifigs" and only <150 parts in "Non-buildable Figures (Duplo, Fabuland, etc)" I think it would be a usability improvement to move them to the latter category. Also logically this makes sense as they are non-buildable in a similar way as the newer Duplo figures.
I see. That problem is known (at least for me ) and I think it's a fault at Bricklink and not at Rebrickable. At least the last time I checked (which is a month or two ago now I think), uploading the xml file resulted in an error, but manually copy/pasting the contents of the xml file in the upload text-area did work. Which makes it seem like there is no error in the xml file, only in Bricklinks file-upload thing. But again, that was a little while ago, maybe something changed in the meantime, I'd have to take a look at it again.
Also, exporting directly to Bricklink without the use of an xml file by going to the Buy tab on Rebrickable and then selecting Export to Bricklink Wanted List also works fine.