Just to give you an update for your makers list.
The Garwood has now changed its name to "The Irish Concertina Company" link for new website is http://www.theirishconcertinacompany.com/
Also Beschäftigungsgesellschaft Klingenthal also know as Schaumufaktur - Klingenthal
are definitely gone as I bought their stock of parts from the receiver.
As regards other listings on your list
The Wren is only a name given to a Chinese made beginner instrument.
The Swan is also made in China they are saying the Voci Armoniche reeds are fitted here,