changing chords_std.xml to display "-7" without correcting to "m7"

Hi -- I've been trying to make my chord symbols look a little nicer in my current font of choice (Montserrat) and used the responses to this post (https://musescore.org/en/node/274326) to change the flat symbols to display as simple lowercase b's in a copy of the chords_std.xml file. The only things I want to change now are the way chord qualities are displayed, specifically changing m7 to -7, Maj7 to Δ7, and Dim7 to o7. I tried following this post (https://musescore.org/en/node/316246) as well to do this, but I haven't been able to get it to work. I know these are very silly nitpicky details and I'm pretty clueless about .xml files so I really appreciate anyone who takes the time to help!