Complex sentence: Initially the term Anglo-German only applied to the concertinas of this type that were built in England, however, as German manufacturers adopted some of these techniques, the term came to apply to all concertinas that used the twenty button system patented by Uhlig.
Split into simpler sentences: Initially the term Anglo-German only applied to the concertinas of this type built in England. But as German manufacturers adopted some of these techniques, the term came to apply to all concertinas that used the 20-button system patented by Uhlig.