This FAQ serves two purposes. Firstly, it does what a FAQ generally does – answer frequently asked questions. Secondly, it is also a place to dump fragments of documentation which haven’t matured enough to be moved into their own documentation file.
The answer is, as often, the nearly useless “It depends”. The built-in modules serve two purposes: On one hand, they should be ready to use and demonstrate the power of FeinCMS. On the other hand, they should be simple enough to serve as examples for you if you want to build your own CMS-like system using the tools provided by FeinCMS.
If a proposed feature greatly enhances the modules’ or content types’ abilities without adding heaps of code, chances are pretty good that it will be accepted into FeinCMS core. Anyway, the tools included should be so easy to use that you might still want to build your own page CMS, if your needs are very different from those of the original authors. If you don’t like monkey patching at all, or if the list of extensions you want to use grows too big, it might be time to reconsider whether you really want to use the extension mechanism or if it might not be easier to start freshly, only using the editor admin classes, feincms.models.Base and maybe parts of the included PageManager...
You enabled the page module (added feincms.module.page to INSTALLED_APPS), run syncdb, and afterwards registered a few extensions. The extensions you activated (datepublisher and translations) add new fields to the page model, but your first syncdb did not know about them and therefore did not create the columns for those extensions.
You can either remove the line Page.register_extensions(...) from your code or drop the page_page table and re-run syncdb. If you want to keep the pages you’ve already created, you need to figure out the correct ALTER TABLE statements for your database yourself.