Since it appears that your custom tab is only used to attach a different template to a document, what happens if you don't share the custom XML, but only


1. leave it in Normal.dotm or

2. put it in a separate dotm in C:\Users\userid\AppData\Roaming\Microsoft\Word\STARTUP?

Something like

<customUI xmlns="schemas.microsoft.com/office/2006/01/customui" onLoad="RibbonControl.Onload"> 
 <ribbon startFromScratch="false">
 <tabs>
 <tab id="CustomTab" label="Transcription">
 <group id="customGroup" label="Templates">
 <dropDown id="attachTemplate" label="Attach template"
 getItemCount="RibbonControl.GetItemCount"
 getItemLabel="RibbonControl.GetItemLabel"
 getSelectedItemIndex="RibbonControl.GetSelectedItemIndex"
onAction="RibbonControl.AttachTemplate" > 
 </dropDown> 
 </group>
 </tab>
 </tabs> </ribbon
</customUI>