I would like to see recorded opposing team rating and rating change, this is displayed in blizzard scoreboard at the end of arena.

This information is already recorded and available in the export: enemyOldTeamRating, enemyNewTeamRating.
Unfortunately, we do not plan on adding it to the in-game table, as we think there is not any room left for it.
But feel free to open a PR if you think you can do it in a nice way.