Leave the app.config.json unedited. The proxy config we have redirects all calls to "/alfresco/*" from the same address the app is running to the proxied address. In your case you change both and then proxy the content that is already coming from the final address.
I don't know if I understand you correctly. As I said before, i have left the app.config.json unedited and tried with the proxy.conf.json . However there the request wasnt sent to 192.168.52.10 but to localhost. And the main problem is, that the request seems to timeout with both addresses.