It seems like local variations of sabers with D-guards were popular in this region (see picture below and those in Leiden).
Otherwise the swords found in museums, like Leiden, are more from neighboring regions like you suggest.
Do a search on "zwaard minangkabau" in the Leiden
database and you will find some swords collected in Minangkabau.
Michael
PS Maybe the reason why there was found a lot of swords from other regions in Minangkabau was because of the tradition that young men left the village for some time to travel around before getting married and settled?