Tabs that are created in code have to be edited in code. But you can create new tabs in the admin area and then assign properties in admin to them although that will de-sync your contentmodels which isn't ideal. Personally a core part of building a well structured CMS and designing the correct tabs/properties and such so I would always have these being designed by the SA/Developers so that everything can be structured in a well design normalized way.
Is it possible to make tabs (groups) in CMS editable? The button in Admin/Config/Edit tabs ist greyed out for all tabs, which were created from code. Customer would like to edit these tabs.