How to check if I’m on a custom post type archive in the admin area

I am trying to alter the query that’s ran on the admin page of my custom post type. This page: /wp-admin/edit.php?post_type=my_venue. Typically, I would use is_admin() && is_post_type_archive('my_venue') to check if I’m on the correct page before modifying the query. However, I have registered my post type with 'archive' => false so now is_post_type_archive() always returns false.

How can I uninstall a language?

I changed my site language a few times for testing purposes. The problem is that after changing it back, WordPress continues to update plugin language packs. How can I uninstall those languages that got installed when I selected them as the Site Language for testing? If I select the Site Language dropdown, I can still see them under “Installed”.

Limit widget to certain sidebar?

I have multiple “sidebars”, but not all of them are the same size. Not all widgets fit in all sidebars (for example, I have a “footer sidebar” where the client can place custom widgets, but they are wide, and don’t fit at all in the “real” sidebar). I want to give an indication when a widget is placed in a sidebar where it would not belong (change the header text color, for example). What would be the best way to do this?