Are tahanan and tawanan (in the hover translation) variants or is the latter just an error?
It's not an error.
tahanan = tawanan = narapidana
Actually, this is the only exercise I got with the tahanan variation. Otherwise tawanan was the only variant I was given in this lesson. Is one variant more colloquial than the other, like "cabai" vs. "cabe"? Or is it a regional thing?