Pardon my "unknowingness" on the DUCO topic. But as far as I'm known to Z-wave by now: Z-wave is a closed protocol for which certification is required and it has a "standard" commandset which can bet queried or which can actively send status updates. Whether or not HS or Vera are able to correctly interpret the information the DUCO devices send back, it should be able to PAIR the devices into the Z-wave network. Unless it's a protocol version issue:
Perhaps it's configured to use Z-wave version 3.20 and higher only, in which case it could make it incompatible with z-wave 2.78 masters (like the Aeon stick or the Vera V1 and Vera V2). The Vera V3 for example is able to speak both 3.20 and 2.78, is it also unable to pair with that?
If you can't fix it with a hammer, you've got an electrical problem!
Fibaro HC2, various z-wave switching, alerting, detection modules.
ELV FHT80b heating system.