Bridge … has ports as members. Ports are ether2 or ether3. When it comes to bridge, VLANs are simply frame headers but beyond that bridge has no notion of vlan interfaces.
Then there are interfaces. Those are entities where router actively communicates with rest of networks. Bridge happens to come with port facing ROS (CPU) and it can have IP address assigned (which then makes it interface). Or bridge port can serve as anchor of vlan ports - assigning IP address to a VLAN port again makes it interface so that ROS can interact with VLANed networks.
But when one enables IP firewall for VLAN traffic, this is sort of extension of firewall functionality (because normally firewall only filters traffic passing via router’s interfaces) … and thus firewall sees traffic coming in via bridge ports. Indeed logs could include VLAN IDs, but that still wouldn’t make them interfaces … even less can those be associated with VLAN interfaces, not every VLAN passing bridge needs a vlan port/interface.
More on different bridge personalities in ROS: http://forum.mikrotik.com/t/routeros-bridge-mysteries-explained/147832/1