With version 14.3.1 I cannot seem to customize the image and logo for ~/umbraco and ~/umbraco/logout. I can get ~/umbraco/login to work using css, app_plugin, and js (https://docs.umbraco.com/umbraco-cms/14.latest/fundamentals/backoffice/login) . There are bugs submitted back in June (https://github.com/umbraco/Umbraco-CMS/issues/16636) that relate to bug https://github.com/umbraco/Umbraco-CMS/issues/17494 that kicks the can. Are there any possible solutions without having to rebuild my own CMS and UI?

Yes, there is a workaround where you inject some CSS into the Backoffice to set the CSS variable

--umb-login-image

. That should work for the logout page. As for the login page, it can be customized using the [Custom background image and logo](https://docs.umbraco.com/umbraco-cms/14.latest/fundamentals/backoffice/login#custom-background-image-and-logo)