Understood. I have not come across this particular issue (probably because I use styles exclusively) so I do not have an immediate solution but, I will continue to research the issue. Hopefully, another user may be able to help you out before then.

//UPDATE// I just went back and reviewed your referenced links from your initial post and found the posts within those links to be a few years old. With the latest comments of those responding to those post being from MSWord MVPs (subject matter experts...IMO) and indicating the use of the backspace key being unreliable in MSWord, I would be inclined to believe that as gospel. Therefore, I would suggest the use of styles as mentioned in my above post.