Handling of weight
"medium" weight in BDF is actually equivalent to Regular in OpenType spec. but fonttosfnt deals with it as "Medium".
For example:
$ fc-query ter-x12n.bdf | grep weight
weight: 80(f)(s)
$ grep WEIGHT_NAME ter-x12n.bdf
WEIGHT_NAME "Medium"
$ fonttosfnt -b -c -g 2 -m 2 -o foo.otb ter-x12n.bdf
$ fc-query foo.otb | grep weight
weight: 100(f)(s)
This looks wrong to me.