I'd neverteless like to see the configi will get in touch with Mikrotik support
Post the CRS config, maybe I can see something there (don't expect too much, though). And the output of /interface bridge port print.
/interface bridge vlan add bridge=bridge tagged=bridge untagged=ether8 vlan-ids=10
Not sure I understand your post, is your question directed at me?PPP frames inside ethernet providing unique layer 2 tunnel based on unicast frames on session level. Why torch should show you destination IP, when PPP tunnel operates only with mac address?
/interface vlan add interface=bridge1 vlan-id=2 name=vlan2 /ip address add address=192.168.2.1/24 interface=vlan2