Assign Shortcut Keys to Script Menu AppleScripts
The macOS has the ability to assign menu shortcut keys in pretty much every application, including AppleScripts listed in the Script Menu of the Media apps. Here's how to do it.
(Hey! If you don't want to do-it-yourself, FastScripts from Red Sweater Software provides the ability to quickly and simply add and manage AppleScript keyboard shortcuts. I highly recommend it.)
Set Up Your System Settings
Note: This will only work with scripts that have been installed in an app's "Scripts" folder such that a script appears in the app's Script menu. See the "Read Me" .rtfd doc that accompanies each script download for instructions on installing or see the online FAQ.
Quit the app. You can't attach a keyboard shortcut to an application if it is running. (Actually, I'm not quite sure of this old rule anymore. Even so, it's a good practice.)
Open your System Settings and click on "Keyboard" in the left column. Click on the "Keyboard Shortcuts..." button in the panel that appears. A new panel will open with a list of options on its left side. Click "App Shortcuts..."
If the app you want to use the script with is not already listed, click on the "+" button and in the Application pop-up of the sheet that appears, select the appropriate app.
In the "Application" popup, select the appropriate app. Enter the name of the AppleScript to which you want to assign a keyboard shortcut exactly as it appears in the Script Menu. In the "Keyboard Shortcut" field, press the combination of keys you want to use for the shortcut.
BUT WAIT! In the recent versions of macOS, there may be a bug afoot. The only way I could get menu items in Music to be recognized was to 1) Leave the "Application" pop up set to "All Applications" and 2) enter the "menu path" to the particular item, "Scripts->Albumize Selection" or "View->as Songs" or "Song->Favorite".
Click the "Done" button and quit System Settings.
The shortcut you assigned will be displayed adjacent to the name of the menu item you assigned it to, just like a real menu shortcut! That's because it is a real menu shortcut.

For more details, search your Mac Help for "Setting custom keyboard shortcuts for applications".
OF COURSE, this isn't just for assigning shortcuts to items in the Script menu. You can also assign keyboard shortcuts for menu commands that don't already have a shortcut. And in this blog post, I describe a cool trick to unambiguously assign shortcuts to menu items in sub-menus.
If you assign a keyboard shortcut which an app is already using you may get mixed results. For example, I assigned Shift-Command-Nwhich is Music's "New Playlist from Selection" shortcutto a script and the script fired (the script is actually similar to "New Playlist from Selection" with additional features). But it wouldn't let me assign Command-A, the universal "Select All" shortcut.
Check out the Missing Menu Commands page for some mini-scripts that work great with shortcuts.
