Not sure what you mean by the Meta key in the context of Windows.
If you mean the
Windows key I suggest you don't use it: a) if you use it in a hard coded shortcut someone (not me) will ask why it's not available in Preferences->Shortcuts; b) many keyboard centric users like me would only use that modifier in utilities that are started at boot time; c) a future release of Windows is more likely to grab it without asking.
But why does it need a keyboard shortcut on Windows. Keyboard centric users will know how to pop the context menu for Replace from the keyboard and then use the down arrow & enter key to open the Saved searches dialogue.
BR