I am trying to migrate from netlify but redirects do not seem to work as well

Question

I am trying to migrate from netlify, but I am noticing small issues which are disrupting the experience.

1 : Redirects
The signin-callback does not get handled smoothly. We have to manually delete the callback. I have a route setup

  "routes": [
    {
      "route": "/signin-callback",      
      "rewrite": "/"
    }

but it does not seem to work as well ... I did notice this

ie i cannot keep configuration changes is that based upon my hosting subscription ? It is not mentioned in the Learn material
The route shows in the configuration ... but unless I manually remove the signin-callback (manual redirect) the page just sits blank. Manual redirect and the user is logged in

2 : Locales

The locales/en-US/json files are not served, they are in an excludes setting. From netlify they are build under /locales/en and served when requested from /locales/en-US do I have to setup all options as rewrites ?
Note the azure app returns a 404 error for any locales information 3 : CORS Issues Chrome and Firefox work OK with netlify but always return a CORS error for the azure app
Edge works OK (bar the above redirect and locales issues).
Is there extra configuration, do I have to create a CDN or domain to handle this ?
Renaming an app on netlify is a very simple process with no CORS issues

Appreciate any assistance