I tested commenting out the registering of the sidebar and it does remove the bar, changing the name and ID and those changes also show. It is only the heading size that does not change from the register_sidebar() function.
The only way that I was able to change the heading size was through the admin interface in the widgets GUI. That does work, but it is supposed to work from the register_sidebar() function as well right? Maybe I am missing something here…so I found a way to do it, but just want to make sure I get the foundations right 🙂
I checked and it seems it is still getting the H2 heading size, but I am not sure from where. I add screenshots of the chrome inspect and of the functions.php file where there sidebar is getting registered.