FWIW just tested in my lab setup (I got a Hex setup with both capsman environments and then AX2 and mAP as APs):
Old capsman with local forwarding -> zero counters on interfaces visible on capsman controller. They do show on local AP device.
Local forwarding disabled and bridge defined in datapath (a.k.a. capsman forwarding) -> counters start to flow on capsman controller. Nothing visible anymore on local device.
It's also noticable when you see the interface line itself on the local AP device.
local forwarding -> interface line is black
capsman forwarding -> interface line is greyed out. Nothing to see there.
So my conclusion is that wave2 behavior is
exactly the same as it was in the past for that local forwarding part.
With a not so insignificant minor detail that capsman forwarding does not exist anymore (yet ?) in wave2-environment. Only local forwarding remains.
Only way I can think of to sort-of "recreate" this local forwarding is to make use of EOIP and force all data to run over there.
AP only able to see capsman controller, nothing else.
Setup EOIP between AP and controller (which is possible since controller can be reached, nothing else)
Attach EOIP to bridge, default route for AP going over that EOIP link.
Result: All AP traffic visible on capsman controller.
Could work, I believe ... another test project