This is my log running Homegear 0.8.0-something vs openHAB 2.2.0-1. Looks good to me. I just pressed once, but kept pressing until the release.
2018-02-01 13:01:13.304 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:13.311 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered
2018-02-01 13:01:13.318 [vent.ItemStateChangedEvent] - AZKEY_CONT1 changed from NULL to ON
2018-02-01 13:01:13.329 [vent.ItemStateChangedEvent] - AZKEY_LONG1 changed from NULL to ON
2018-02-01 13:01:13.333 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:13.527 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:13.531 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:13.784 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:13.791 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:14.134 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:14.140 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:14.311 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:14.318 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:14.583 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:14.603 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:14.800 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:14.808 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:15.068 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:15.072 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:15.320 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:15.328 [vent.ItemStateChangedEvent] - AZKEY_LONG1 changed from ON to OFF
2018-02-01 13:01:15.331 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:15.587 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:15.594 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:15.846 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:15.859 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:16.093 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:16.102 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:16.366 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:16.372 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
==> /var/log/openhab2/openhab.log <==
2018-02-01 13:01:16.689 [WARN ] [virtual.PressVirtualDatapointHandler] - Unknown value 'CONT' for PRESS virtual datapoint, only SHORT,LONG,LONG_RELEASE allowed
==> /var/log/openhab2/events.log <==
2018-02-01 13:01:16.693 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG
2018-02-01 13:01:16.703 [vent.ItemStateChangedEvent] - AZKEY_LONG_RELEASE1 changed from NULL to ON
2018-02-01 13:01:16.707 [vent.ChannelTriggeredEvent] - homematic:HG-HM-PB-2-WM55:homegear:OEQ0486825:1#PRESS triggered LONG_RELEASE
Maybe this is a different bridge behaviour? Do you run the latest CCU2-Firmware with your piVCCU?
The behaviour of the multiple PRESS_LONG events is fine, you can increase/decrease brightness/volume with that.