OK, adding the ip address was the next step
It doesn't make sense tough, the upstream interface doesn't need an ip address, this is theoretically not needed for igmp-proxy to send multicast flow to the tv decoder interface (the french config template doesn't have one for instance).
About the lag you still have, well I went as far as I could. Compared to your first config, I edited the missing mss-clamp part and removing unnecessary mtu (could have caused packet fragmentation), removing egress-qos for data vlan (not need in France for PPPoE connections) from what I can remember.
I don't have anymore clues about why you still have freeze or lag during web browing because the multicast tv flow is prioritized over data flow.
There maybe difference between France and Poland architecture explaining this but this goes well beyond the help I can provide.