First, long ago I became frustrated with envelopes in Word because I wanted to be able to have multiple return addresses. I created envelope templates that looked the way I wanted and which have
MacroButton Field prompts for me to fill in for the addressee. If I wanted to keep an envelope I would simply save the envelope created from the template in a folder labeled envelopes with a document name showing the addressee. In other words, I bypassed the Word envelope function.
I currently have a macro attached to my QAT which creates a new document based on the envelope template.
I do not know where that 2" indent comes from. It is not part of the style setting for Envelope Address in the normal template. That style is changed by the use of the envelope button and is apparently hard-wired into Word. The frame is created to be horizontally centered on the page with a 2" indent inside the frame. I suspect it is designed that way so that it will work on smaller envelopes, but I certainly understand your not liking it. I believe this is a bug and it has been there since at least Word 2010.
If you download the Envelope tutorial at the bottom of the tutorials on my
downloads page, it has a sample envelope template. Although that template is dated in that it contains an obsolete POSTNET barcode, it otherwise works fine. You could adapt it to your use. At least it would let you see what I mean by an envelope template. Although it contains macros, you can use it without them being active or allowed to run. You can change the frame used in the template to suit your needs.
To record a macro that uses your template, save the template in your Custom Office Templates folder. It should be saved there by default when you save as a template. Start recording the macro and create a new document based on the template. Stop recording. You can save an icon for the macro on your QAT.
The functions of the Envelope Wizard discussed in the tutorial have been supplanted by the mailings tab button.