Your component is throwing a number of deprecation warnings in the console, so you should look at those.
More important, it’s overriding quite some HBS templates. You should analyze the changes for these templates between the version the theme component was built for, and the current version of Discourse, and synchronize the changes (or copy the templates and re-apply your own modifications).
To be honest, at a first glance it would be better if you (at least partly) rewrote the theme component to make better use of plugin outlets.