I've just updated to version 220.127.116.11 of Fony and it seems that I cannot import any Bitmap Font Writer fonts- including the ones I've made and the fonts shipped with BFW. The error says: This bitmap is not in a bitmap font writer format.
Also there doesn't seem to be an BFW export option (which I thought was included in 18.104.22.168.
I was able to import BFW font no problem this time. I also found the BFW export in File > export > bitmap > tick in Bitmap Font Writer format option. I initially looked for it as a separate export option.