Sorry it took me a day to get back to you,
I think highway=pedestrian is better tagging since these features represent the areas of sidewalks so they are pedestrian areas and if one were to add a new one in iD (or any other editor using the iD tagging schema) would add a new pedestrian area using  the tags of area=yes and highway=pedestrian so that tag should stay. That’s why I didn’t change/remove the area:highway=pedestrian since the area*=* is technically correct so that’s why I feel it would be optimal to keep the tagging before this change.
Happy mapping 