Actually I believe host networking would be the one case where this isn’t an issue. Docker isn’t adding iptables rules to do NAT masquerading because there is no IP forwarding being done.

When you tell docker to expose a port you can tell it to bind to loopback and this isn’t an issue.

I don’t use the WebOS app but generally default subtitles/audio languages are set on your profile and the apps pick up those settings.

Try logging in to the web interface and going to your user profile. There is a “Playback” section where you can set your preferred languages. If this isn’t set it likely is taking the default language from your media files instead.