Localisation with App Proxy

@SBD sorry to stress but we kinda moved our Shop over from Magento 2 recently and now all of our spanish/italian/portoguese/danish/norwegian/swedish/polish customers have to use the shop in English which lead to a significant drop in our conversion rate.
It’s because our product pages are implemented through an app proxy (as it’s a customized product)

Would appreciate if you could give a rough estimate when this can be fixed