The only stupid questions are those not asked.
- you have only got a single /56 pool, the one you have requested and received from the Starlink DHCPv6 server.
- to let hosts connected to bridge have their IPv6 addresses, you do not need to use DHCPv6, nor you actually could use it until ROS 7.17+ (the first one where DHCPv6 server supports leasing addresses to clients, not just prefixes). SLAAC is normally sufficient for hosts that are not routers or really specific endpoints.
- if you do insist on using DHCPv6 to lease addresses to hosts connected to bridge, you must use the same pool that you’ve asked the DHCPv6 client on WAN to fill.
- the DHCPv6 server does not indicate a route; Mikrotik’s “add default route” setting of the DHCPv6 client works with the assumption that the DHCPv6 server is colocated withe the router, which is not the case for Starlink. But the link-local address I gave above works for all terminals.
- to be able to ping the router, it is enough that you assign the IPv6 address to the bridge, there is no need to assign another one to the WAN interface.