Cheers!

        <Item id="0"/>
        <Item MenuEntryName="Language" subMenuId="language-userDefinedLanguage" name="User Defined Language" MenuItemName="dBASEPlus_Dark"/> 
        <Item MenuEntryName="Language" subMenuId="language-userDefinedLanguage" name="User Defined Language" MenuItemName="dBASEPlus_Light"/>

This seems to me to be the quickest easiest way to do this kind of thing and it’s always available with a right mouse click and selection.

But there was part of my response that I think might be useful to future readers of this topic, as it’s not as commonly understood:

When using notepad.runMenuCommand(...) in the PythonScript plugin, it is using the actual text from the menu names. Thus, it is affected by Settings > Preferences > General > Localization – thus, using the XML example above, in the default English localization, it would be notepad.runMenuCommand("Language", "XML"). But if you were in Pig Latin (for example), it would have to be notepad.runMenuCommand("Anguagelay", "XML"); or if you were in Greek, it would have to be notepad.runMenuCommand("Γλώσσα", "XML")

(Aside: there’s actually a quirk, though: if you have switched from, for example, Pig Latin to Greek, then until you restart Notepad++, you can use either the Pig Latin or the Greek menu-name-strings in your runMenuCommand calls. Once you restart Notepad++, you can only use the active Localization for those strings.)

(I don’t know if Localization was actually the problem in the now-deleted post, but it might have been, and it could easily be a problem for other users as well; This actually came up recently, and since it has bearing on this discussion, I thought I would share that main idea here, too: if you are using Localization other than English, you will have to adapt any runMenuCommand calls in your PythonScript scripts to use the actual name of the menu in your GUI, not the English names – whether or not it would have solved the deleted problem, it’s important enough to share.)

The PytonScript was a little wonky with allowing me to set the icon. It seemed committed to .bmp or .ico files rather than .png. Ok – found those alternatives. But each time I tried to load them, it just didn’t work. But hey – that’s more the plug-in…

Your solution worked like a charm! Thank you!

The languages don’t show up in Settings > Shortcut Mapper, so the easiest possibility isn’t there.

The language change doesn’t seem to get recorded in a macro.

I think the issue is that they don’t have a static menu command ID (ie, aren’t listed in menuCmdID.h), so there isn’t a direct way to call them.

However, some of the scripting plugins, like PythonScript (install instructions here), do have a way to search the menus for an existing command, even if they don’t have a static command ID.

PythonScript’s notepad.runMenuCommand("Language", "YAML") will change the language to YAML; any languages at the same level will have the same syntax. If you have Preferences > Languages > ☑ Make language menu compact enabled, then the languages under a letter submenu will require a trick: for example Languages > N > Normal Text would be accessed via notepad.runMenuCommand("N", "Normal Text").

So, if you install PythonScript, then Plugins > Python Script > New Script, and create these two scripts:
SetLanguageSQL.py

from Npp import *
notepad.runMenuCommand("S", "SQL")

SetLanguagePowerShell.py

from Npp import *
notepad.runMenuCommand("P", "PowerShell")

Then Plugins > Python Script > Configuration,

• click on SetLanguageSQL.py and ADD to the Menu Items list
• click on SetLanguagePowerShell.py and ADD to the Menu Items list

Once there, restart Notepad++.

Now Settings > Shortcut Mapper > Plugin Commands will list those two scripts, and you can associate them with keyboard shortcut of your choice.