You're talking about captured Czech and French and Polish and other tanks, the supply chains and production lines of which they actually took over, right?
They used everything they could get their hands on. For example: http://www.achtungpanzer.com/panzerkampfwagen-t-34r-soviet-t-34-in-german-service.htm
As I said elsewhere, just because Germans captured the T34 doesn't mean they should get it as a faction.
For hetzers they captured the production lines so could manufacture accordingly. Though Czech tanks, they were and are associated with the German armed forces.