I think it would be good if you could share your box with us so we can make a better rating and we can suggest alternatives to your units that can increase your team's capability in geared and ungeared pvp. As Jackiedubs553 said you can utilize Traitor Meli's unique ability better if you have another good hard hitter in your team as much as I like Red Sariel it feels a little weaker and out of place with the current meta that is going on right now. Since I can see that you rely on Red King's unique ability for greater pierce rate and that's why you use Sariel I'll strongly suggest Deathpierce for a subslot (if you have the unit) instead of Red King to bolster your team's damage output better since it helps decrease the enemy's team crit resistance and crit defense by 30%. You can try it in a friendly match to see which team is better to help you compare which team to use in the future. As FlamingDevStudio stated it is also good if you have Margaret Ludociel as a substitute for Red Sariel since its unique ability increases goddess' allies basic stats by 8% every time they use a buff or stance skill (just check out Margaret Ludociel's page to see more info). The only downside with that is if you don't have the unit or you have not invested enough to make it good in pvp.
This team comparison is assuming that your units have maxed out level and super awakening with good ult level and best sub and appropriate gears equipped for elite pvp. Please also take this with a grain of salt as this is only a conjecture based on the current meta.
Your team with Red Sariel and Red King is weak against a team with attack removal and buff removal. Since your former team relies on Red King's unique if you went against a team with attack removal you are already at a big disadvantage which implies youll be at a disadvantage against players who uses attack removal teams. You will also be at at a disadvantage against players who uses Hijack Gowther with it's Jack Light card. I don't know how you fare against Festival King teams since I have never seen you explain how you win against those teams.
With Margaret Ludociel and Deathpierce you should be able to dish out better damage while also having a better support hitter unit with Margaret. Your only disadvantage now would be in teams against with both attack removal and buff removal since Margaret and Goddess Elizabeth have both buff cards and no cleanse cards. Margaret also increases your team's damage output with her buff card which also serves as a debuff card at the same time.
If possible send out screenshots with your box units and your team with its gears and sub units with gears so we can see better and make better suggestions. Well then, have fun gaming with 7DSGC!