F5 introduced the 'mv' command in 11.6.0, which should allow you to change the name of one of your two traffic groups. An earlier thread for this question can be found here.
If the warnings about the 'mv' command have you concerned, I would suggest that rather than renaming one of your two traffic groups, you create a replacement group and then move all of the failover objects into your new traffic group. You could create all the commands offline and then paste them into the CLI, making the translation as quickly and error free as possible.