Personally I think your formation is a bit messy, it is still a perfectly good and has its merits. Though swapping SVD for a powerful AR (G41, G11, etc) will achieve high DPS at the cost of losing a RF's back line targeting priority. Also while using an HG can give better buffs than a SMG, they die very quickly on higher levels if you don't kite enemies.
Overall I prefer and recommend using echelons that focus on one class of DPS unit rather than mixing and matching trying to support two very different classes of DPS
I hope this helps
Also as a side note you seem to have a bit of a focus on 5* units, don't forget that there are many top tier dolls of lower rarity.