Text Doc from Template SS substitution keys

I am not sure what you are looking for.

In case your placeholders do not work, this is because the logic in Appian works on raw text that includes the XML formatting. To make it work, you have to make sure that a placeholder does NOT contain any formatting inside.

There is a longstanding bug (since at least 10 years ago) in the Word Docx from Template smart service where Appian will "see" the replacement key name from the Word Template but will not filter out any background WordML markup language that has inadvertently been included "inside" the key name.  The worst offender for causing this is having Spell Check enabled in Word while making any additions / changes to a template, as each key is apparently bound to become cluttered with markup after such changes. 

This becomes important when making updates to a template because even if the plaintext key name is unchanged, any change to the random junk WordML "inside" the key (which you can only see in "View Documentation" for the process model, iirc, and if you open the "word/document.xml" xml file from within the document's zip file), cause the new template version's existing replacement key(s) to NO LONGER MATCH, and will actually clear themsevles out when refreshed.

It seems that the issue you are facing is a longstanding bug in the Word Docx from Template smart service in Appian. This bug causes the replacement key names to include background WordML markup language that should have been filtered out.

One possible cause of this issue is having Spell Check enabled in Word while making changes to a template, which can result in cluttered markup within the replacement keys.

To address this issue, you may need to manually remove the unwanted markup from the replacement keys in the Word document. Alternatively, you can try disabling Spell Check while making changes to the template to prevent the cluttering of markup in the replacement keys.

Please note that this bug has been present for at least 10 years, so it may require a workaround or further investigation from the Appian support team to resolve it permanently.