There has been a few occasions already where we use one card in place of another in OP either as a henchman or as a normal boon that gives a chance to close the location.
Rather than try to remember which boon is the special one or to ignore what it says on the henchman card and do what the scenario says would it be possible to get a set of eight generic henchman cards to cover this function.
Probably this would be via "Drive Through RPG" like the errata cards. Cards really just has to say "Refer to scenario special instructions" or something similar.
This would put less strain on my less than perfect memory.