This syntax is not supported, but you can add the resx localization files of RadEditor in the \inetpub\wwwroot\wss\VirtualDirectories\80 folder, open the \Program Files\Common Files\Microsoft Shared\Web Server Extensions\wpresources\RadEditorSharePoint\18.104.22.168__1f131a624888eeed\Resources\App_GlobalResources\RadEditor.Tools.resx file and register the SPTemplateManager property in it with the desired localization text.
You can find more information in this article: Using Global Resource Files
. You should also remove the text attribute from the SPTemplateManager tool tag in the toolsfile.
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